FLYING FISH GROUP 4: FISH
... ORDER ~ FAMILY ~ Cyprinodontiformes "'1IIIIIIII Exocoetidae
GENERA Exocoetus, Thoracopterus, Fodiator, etc.
Flying fish have an extraordinary way of escaping from enemies. They accelerate across the ocean surface like a seaplane, then
spread their fins and glide above the water to safety.
KEY FACTS
SIZES Length: Up to 18 in. (California
flying fish) . Weight: Up to 1 ~ lb.
BREEDING Mating season: Spring and early summer in warm and temperate waters. Eggs: Free-floating in oceanic species. Filaments on eggs of shallow sea species catch in floating vegetation or debris.
LIFESTYLE Habit: Sociable, but does not swim in tightly organized schools. Diet: Small planktonic animals, including the larvae of other fish.
lifespan: Unknowri.
RELATED SPECIES There are about 48 species of flying fish of various genera worldwide. The most closely related species are the tropical halfbeaks and the needlefish.
FEATURES OF FLYING FISH Tail: Enlarged , powerful lower lobe. Used to build up momentum that allows fish to clear the water.
Fins: Large pectoral fins fold back along body when swimming and spread out rigidly when "flying." Pelvic fins are also large in
© MCMXCI IMP BV/IMP INC WILDLIFE FACT FILET ...
Range of flying fish .
DISTRIBUTION
Flying fish occur in theyopical zones of all the major oceans. The Atlantic flying fish often moves into northern waters
around Europe and North America in late summer and leaves when the water cools in early winter.
CONSERVATION Although the California flying fish has some commercial
value as bait for game fishing, no species is in direct danger.
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HOW A FLYING FISH GLIDES THROUGH THE AIR
1. Approaches surface of the water at an angle, vibrating tail to build up momentum.
2. Spreads fins and glides for several feet.
3. As a flying fish loses momentum, it may touch its tail down in the water, regaining propulsion to continue its flight.
0160200441 PACKET 44
Flying fish live mainly in tropical oceans, where
they are favorite targets of predators such as tunas,
sharks, and seabirds. Their celebrated skill in the
air often helps them escape underwater attackers.
But their prowess at "flying" may carry them away
from one enemy, only to deliver them into the
jaws of an airborne predator.
~ HABITS While feeding in surface wa-ters, flying fish are targets for tuna and bonito, which hunt in packs in warm seas. To escape these predators, flying fish leap out of the water and glide over the ocean surface.
Their "wings" are large pec
toral fins and, in some species, pelvic fins. The fins are usually folded back along the fish's flanks. But when it "flies," the fish holds its fins out stiffly, like airplane wings.
As it propels itself through the water, a flying fish builds up momentum until it can glide through the air.
As it breaks the surface, the fish speeds up by vibrating
the lower lobe of its tail fin in the water. Then it spreads its "wings" and glides clear of the waves for several seconds before touching down.
The average "flight" lasts two to three seconds, but longer flights are common, sometimes lasting 10 seconds and covering over 30 feet. While flying is an ideal way of escaping from predatory tuna, it puts the fish in jeopardy from ocean birds such as the albatross and frigate bird, which snatch flying fish as they leap from the water.
Right: Flying fish are most common in tropical waters, despite the scarcity of food.
~ BREEDING In the Mediterranean, the At-lantic flying fish spawns from May to July. The eggs are covered with fine threads, or filaments, that anchor them to floating objects so they do not sink to the seabed.
All coastal species of flying fish have similar eggs. But the eggs of open sea species have much
Left: By flicking its tail back into the water, a flying fish can continue its flight for some time.
DID YOU KNOW? • When accelerating for takeoff, a flying fish vibrates its tail at a rate of over 50 beats per second.
• A record flight of 42 seconds covered 2,000 feet.
• Some marine predators, like dolphins, outwit a flying fish by swimming along its
shorter filaments that act like parachutes, slowing down the eggs as they sink in the water. The eggs hatch while sinking, and the larvae drift back to the surface to feed on plankton.
Unlike their parents, young flying fish are often brightly colored, with shorter pelvic and pectoral fins and a long barbel trailing from the chin. In one species the barbel is longer than the body of the young fish .
path at high speed. When the fish reenters the water, the predator is waiting for it.
• Flying fish have been found on ship decks over 30 feet above sea level. They may reach this height by taking off into the wind and being swept up by air currents.
Above: A flying fish uses both pectoral and pelvic fins to power its "flight."
Left: A flying fish clears the water easily as it glides, escaping underwater enemies.
~ FOOD & FEEDING Most flying fish live in the warm oceans of the tropics, where they eat zooplankton -tiny floating animals such as copepods and the larvae of crabs and fish.
Flying fish gather in areas where currents carry nutrients up to the surface waters. The nutrients are eaten by zooplankton, which in turn are eaten by flying fish.
Flying fish feed in the upper parts of the ocean, where plankton is densest. They strain water through their gill rakers to filter out edible particles. Larger plankton eaters such as whale sharks may join the flying"fish when feeding.
BASKING SHARK
ORDER Lamniformes
FAMILY Cetorhinidae
GROUP 4: FISH GENUS &: SPECIES Cetorhinus maximus
The basking shark may look more fearsome than its smaller, more fierce relatives. But despite its cavernous mouth and huge
dorsal fin, it is a placid, harmless giant.
KEY FACTS
SIZES Length: Averages 25-30 ft. Weight: 4-4Y.1 tons.
BREEDING Sexual maturity: 2-4 years. Mating season: Spring in the North Atlantic . Gestation: May last 3 years. No. of young: 1, occasionally 2.
LIFESTYLE Habit: Occurs singly, in small groups, or in schools. Slowmoving; often appears at the surface. Diet: Plankton. lifespan: Not known.
RELATED SPECIES The basking shark is in a family by itself. But it is related to thresher sharks and mackerel sharks.
Range of the basking shark.
DISTRIBUTION
Found in temperate waters in both the northern and southern hemispheres.
CONSERVATION
The basking shark is thought to be low in numbers, but there are no accurate details about population figures. There is some concern that fishing may be reducing the basking shark's feeding areas.
SPECIAL ADAPTATIONS OF THE BASKING SHARK
Gill rakers: Sticky, mucouscovered bristles trap food.
Filament: Thin layers of orange-red flesh that absorb
en from the water.
Feeding: Water, oxygen, and plankton are sucked into the mouth and filtered through the gill rakers. The rakers trap the food but allow the water and carbon dioxide out through the five gill slits on each side of the mouth.
© MCMXCI IMP BV/IMP INC WILDLIFE FACT FILETM PRINTED IN U.S.A.
Gill rakers
Filament
0160200401 PACKET 40
cruising near the surface of temperate oceans
with its giant mouth wide open.
Despite its huge size-up to 30 feet-it feeds
only on tiny sea creatures that it filters
from the water.
~ FOOD & FEEDING Sharks are renowned as fierce predators. Yet the two largest species, the basking shark and the whale shark, have a completely different feeding behavior. Like manta rays and great baleen whales, they sustain their enormous bulk by swallowing great quantities of plankton-tiny ocean creatures that include fish eggs, copepods, and arrow worms.
By cruising gently through the ocean with its great mouth
yawning open, the basking shark draws in tons of water. The water passes out through five wide gill slits on each side of the shark's neck after it has been strained through rows of gill rakers. Thousands of these mucous-covered bristlelike structures lie next to the gills. Each is about four inches long. When the basking shark opens its mouth, the gill rakers spring up to form dense fringes that trap the tiniest prey.
The basking shark is known for cruising slowly. It rarely swims faster than three miles an hour and is often seen at the surface of the water. It is named for its habit of lying still-its back breaking the surface and its great dorsal fin protruding-as if it were basking in the sun. Although they are often seen alone or in twos and threes, basking sharks sometimes gather in schools of 50 or even more than 100
individuals. Basking sharks are seen
most often in summer, when temperate waters are rich in plankton. In winter this food supply dwindles, and it is thought that the sharks cannot take in enough plankton to remain active. Instead, they may retreat to deeper water or
DID YOU KNOW? • The basking shark is the second-largest fish in the world after the whale shark.
• The largest basking sharks on record include a 39-foot specimen trapped in a net off southeast Canada in 1851, another 39-foot shark caught off Portugal in 1865, and a 45-foot giant caught off Norway in the 1890s.
• Cruising at about 2 knots, a basking shark can filter 1,000 tons of seawater through its mouth in an hour.
l eft: The basking shark is a gentle giant of the ocean.
Front cover inset: The basking shark's wide, gaping mouth acts like an enormous sieve.
possibly the sea floor. There they lie still and stop feeding . Their metabolic rate drops, and they rely on deep currents to bring oxygen to their gills. In European waters basking sharks appear to shed their gill rakers in winter, making feeding impossible. By spring, when plankton starts to flourish again, they have acquired new gill rakers.
~ NATUREWATCH Basking sharks are summer visitors to both the Atlantic and Pacific shores of North America, in coastal and offshore waters. They start to appear in late April and early May, when marine copepods, a staple food, are
• There are reports of basking sharks leaping completely out of the water. They may have been trying to drive off parasites, such as lamprey, attached to their bodies.
• Basking sharks have never been major fishing prey. But some have been fished off Ireland, Scotland, and Norway. The liver from a single shark can weigh 1,500 pounds and yields valuable oil.
~ BREEDING Little is known about the breeding behavior of the basking shark. It IS known, however, that egg production is strikingly different from that of most sharks.
Sharks generally produce a small number of large eggs. But a female basking shark
may produce six million eggs that are 0.02 to 0.2 inches in diameter. Fertilization is internal, and the young seem to develop inside the mother's body, as in most sharks. Why the female produces such a huge number of eggs is unclear. It may be that the
abundant near the surface. By the end of November,
the basking sharks have disappeared, probably to deep water for a long winter fast.
The tall dorsal fin and the sheer size of a basking shark make it easy to recognize.
Above: To nourish its huge body, the basking shark spends a large amount of time feeding near the surface of the water.
mass of unfertilized eggs provides nourishment for the developing embryos.
The end result is only one or two offspring. At birth, basking sharks are already about five feet long. Immature sharks can grow up to 15 feet. At this stage the
sharks have long, fleshy snouts, with a curved hook at the tip. Basking sharks generally reach sexual maturity when they are 15 to 20 feet long.
Below: A system of gill rakers ensures that no food escapes the basking shark's mouth.
"" CARD 33 RUDD ~~ ___________________________________ G_R_O_U_P_4_:_F_IS_H __ ~ .. ORDER ... FAMILY .. GENUS &: SPECIES ~ Cypriniformes ~ Cyprinidae ~ Scardinius erythrophthalmus
The rudd is a resilient, adaptable fish that thrives under the most difficult of conditions. It often appears as if by magic in the
seemingly barren waters of newly flooded quarries.
KEY FACTS
SIZES
Length: Average, 6-12 in.
Weight: Average, 1 lb .
BREEDING
Sexual maturity: 2-3 years.
Spawning: April to June.
Eggs: ~o in., round. They stick to
vegetation .
Hatching period: 8-15 days.
LIFESTYLE
Habit: Surface-feeders. Swim in
small schools.
Diet: Crustaceans, aquatic insects,
flying insects that land on water,
some plant matter.
lifespan: Up to 10 years.
RELATED SPECIES
A member of the carp family, its
nearest relative is the very similar
roach, Rutilus ruti/us.
HOW THE RUDD FEEDS
Range of the rudd.
DISTRIBUTION
Basically a European species, the rudd is found from Ireland
and southern England through France, Italy, and Greece to
western Siberia and north to Sweden.
CONSERVATION
The rudd is not threatened, either directly or indirectly. It is a
very resilient fish and can survive in waters with relatively high
levels of organic pollution.
Surface feeding: The rudd 's sharply angled mouth allows it to feed on insect larvae that float on the surface of the water.
Spawning: Between April and June the rudd lays sticky, mucus-covered eggs that float downstream and become attached to water plants.
position of its mouth, the rudd can take food from the bottom
. only when swimming vertically.
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The rudd is a small surface-feeding member
of the carp family. Like all of its relatives, it can survive
in large, slow rivers and lowland lakes that contain
little oxygen and are often polluted with fertilizers.
In these waters, the rudd is a major predator of
insects and other small aquatic animals.
Basically a still-water fish, the
rudd is found in lowland lakes,
ponds, and river backwaters. It
is especially common in man
made lakes and channels such
as flooded gravel pits and drain
age ditches. These waters are
usually rich in plant nutrients
like nitrogen and phosphorus
that come from decaying plants
and animals or from fertilizers
washed off of adjoining farm
land. The plant nutrients pro
mote lush growths of water
plants on which the rudd feeds.
As a result, these neglected,
overgrown waters often teem
with rudd.
The abundant plant nutrients
also help to create clouds of mi
croscopic floating algae. When
the algae die and rot, the de
caying action of organisms like
bacteria can use up a great deal
of oxygen in the water. While
many fish become ill or die in
such conditions, the rudd is
able to feed and thrive.
The rudd can also survive in
waters where the food supply is
inadequate for most fish. Small,
depleted lakes in soft-water areas
often harbor large schools of ap
parently half-grown rudd, whose
growth has been stunted by
poor nutrition.
~ FOOD & FEEDING Although the rudd eats some
plants, it feeds mainly on insects
and small aquatic crustaceans
such as freshwater plankton.
The rudd usually feeds in mid
water or near the surface. On
hot summer days large schools
of rudd can be seen just be
neath the surface preying on
Left: The rudd can be identified by its protruding lower jaw.
~ ENEMIES In lowland lakes the rudd preys
on insects and other small wa
ter animals. In turn, it is preyed
on by larger fish such as perch
and pike. Rudd are most vulner
able when young. While barely
mobile, a large proportion of
young, called fry, are eaten by
other fish. When they grow big
ger, rudd are harder to catch.
Since they are surface feeders,
rudd are easily seen from above
by fish-eating birds such as the
heron. The rudd that colonize
gravel pits provide a steady
source of food for the great
crested grebe. Small rudd in
river backwaters often fall prey
to kingfishers.
Fishermen often catch rudd,
which rise to their bait. Since
rudd are not usually eaten,
however, most of the fish are
thrown back.
small floating insects such as
mosquito larvae. In summer
large rudd are a major threat to
the young fish that feed on the
tiny planktonic animals swarm
ing beneath the surface of rich
lowland lakes.
The rudd's steeply angled
mouth is ideal for snapping up
flies that fall into the water, but
it is ill suited for feeding on the
~ BREEDING & GROWTH From April to June rudd move
into shallow waters to spawn,
often congregating in large
schools around submerged
plants. The fish may be seen
rolling at the surface as the
males weave through the
schools, fertilizing the eggs.
The transparent eggs become
attached to water plants, which
helps prevent them from being
eaten by predators (including
other rudd) or being swept
away into unsuitable waters.
The eggs hatch in 8 to 15
days, depending on the water
bottom. Like all its relatives in
the carp family, the rudd lacks
teeth in its jaws. Instead, it has
bony knobs mounted on bones
on each side of its throat. It
grinds these knobs against a
hard, horny pad in the roof of
its throat to crunch up insects.
Below: Rudd thrive in warm water and often congregate at water outlets near power stations.
temperature. The emerging lar
vae look like tiny, transparent
fry. Each larva has a yolk sac
with nutrients that sustain it
during its first days of life. The
tiny fish then begins to feed on
microscopic floating animals.
At a year old, the young fish
DID YOU KNOW? • Rudd found in isolated
gravel pits may arrive as
eggs, stuck to the feet of
birds that fly in from lakes.
• Spawning rudd often
get mixed up with roach
and bream, and many
eggs develop into hybrids
that share the characteris
tics of both parents.
are about three inches long
and begin eating plant food.
They soon start eating insects.
If food is abundant, they may
grow up to 18 inches long. But
since most rudd live in poor
conditions, the mature fish are
usually much smaller.
STICKLEBACK GROUP 4: FISH
... ORDER ~ Gasterosteiformes
... FAMILY ~ Gasterosteidae
... GENERA & SPECIES ~ Gasterosteus aculeatus, etc.
Sticklebacks are named for their dorsal spines, which may offer some protection from predators. In the breeding season the males
become brightly colored and care for the young.
KEY FACTS SIZE
Length: Usually 2 in. Rarelyex
ceeds 4 in., but 15-spined stickle-
back can reach 8 in.
BREEDING
Sexual maturity: At end of first
year (3-spined stickleback).
Mating season: Spring to summer.
No. of young: Each nest of the 3-
spined stickleback yields approxi
mately 100 young.
LIFESTYLE
Habit: Lives in loose schools except
in the breeding season, when the
male is territorial.
Diet: Aquatic invertebrates; occa
sionally waterweeds.
Lifespan: 3-spined species lives to
3 years.
RELATED SPECIES
There are 5 species of stickleback in
5 genera.
STICKLEBACKS' NESTS
Nine-spined stickleback: The male makes a rounded nest from algae and weeds in vegetation near the riverbed or seabed. He binds the materials together with a sticky substance from his kidneys.
Female: Lays eggs, but male cares for eggs and young when they hatch.
Three-spined stickleback: The male makes a moundlike nest from weeds in a hollow on the riverbed or seabed.
•
© MCMXCII IMP BV/ IMP INC WILDLIFE FACT FILETM
Range of the three-spined stickleback.
DISTRIBUTION
The five stickleback species can be found in fresh and coastal
waters throughout the Northern Hemisphere.
CONSERVATION
All sticklebacks suffer from the pollution and draining of their
habitats. Although some species are restricted in their distribu
tion, none are seriously threatened.
'--_~-=-':' ___ Throat: Ninespined stickleback's throat deepens from brown to black during breeding.
~ __________ ~ __ Belly: Three-
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spined stickleback lures a female to the nest with his
' . bright red belly and blue eyes.
0160200641 PACKET 64
Sticklebacks are some of the most familiar fish of the ~ ~ BREEDING
Northern Hemisphere. They are able to live in fresh water Sticklebacks breed from late
as well as salt water, and some species occur in both
kinds of habitats. These adaptable fish can be found
in even the smallest ponds and ditches.
~ HABITAT Sticklebacks can be found in a wide range of watery habitats, from ditches and the edges of lakes to the sea. Only one species, the fifteen-spined stickleback, is never found in fresh water and spends its life at sea.
The most familiar species is the three-spined stickleback. It occurs in most of the Northern Hemisphere, living in streams, rock pools, and ditches. It usu-
ally stays near the shore, but it is sometimes found at the surface in the open sea.
Sticklebacks often live in loose schools, except in the breeding season, when males become fiercely territorial. All sticklebacks have spines that may provide some protection from predators, but they still fall prey to water shrews, otters, larger fish, and certain water birds.
March to early August, when food for the young is plentiful. Some species migrate from the sea to breeding grounds in rivers and streams. Those that do not migrate breed where they spend the rest of the year.
In most species, the male takes on bright coloring and becomes very territorial during breeding. He builds a nest on the bottom or among waterweeds and then entices females to enter this nest.
The females lay their eggs in the nest, and the male fertilizes them. He guards the eggs and the young when they hatch, tending them for a few weeks until they are independent.
Above: 5tickleback eggs three days after fertilization .
Above right: A young stickleback with its yolk sac.
Right: A male stickleback cares for his week-old young.
~ FOOD & FEEDING
Sticklebacks have a varied diet. They feed primarily on small aquatic animals such as insect larvae, crustaceans, small mollusks, and worms. They also eat young fish and fish eggs, including other sticklebacks' eggs.
Sticklebacks hunt at night, watching for the movement of prey. They need good light for hunting and probably feed only when the moon is bright.
When sticklebacks spot a potential meal, they chase it if necessary and seize it by suddenly pushing their jaws open. The jaws are protractile (stretching out away from the mouth). After the prey is sucked in, the fish grabs it with small, needlesharp teeth.
When one stickleback finds food, others rush to join it, because there may be more food in the area.
left: A three-spined male tends his nest of woven weeds.
Below: A male stimulates his mate to lay eggs in the nest.
DID YOU KNOW? • Sticklebacks are caught for uses other than food. They are made into oil and animal feed and may be used as fertilizer. • Freshwater sticklebacks are usually smooth, but many sticklebacks living in salt water have thin, bony plates on their sides. • Sticklebacks can be pests. In the Black Sea region of Europe, the three-spined stickleback eats the young of fish that are caught for human consumption. It also competes with these fish for food. • Sticklebacks that spend time in both fresh and salt water must deal with differences in water salinity. They do this by maintaining a certain concentration of salt in their body fluids -a function carried out by their gills and kidneys.
VIPERFISH
ORDER Stomiiformes
FAMILY Chauliodontidae
GENUS Chauliodus
Viperfish live more than a thousand feet below the surface of the ocean. These deadly predators are well adapted for hunting
other fish in the dark waters of the ocean depths.
KEY FACTS
SIZES
Length: Up to 1 ft.
BREEDING
The breeding habits of viperfish are
not known. They are thought to
produce large quantities of eggs
that hatch into larvae before be
coming adults.
LlFESTLYE
Habit: Solitary, slow-swimming
predators, usually found at depths
of 1,300-2,600 ft.
Range of viperfish. Diet: Various deep-water fish,
some of which may be as large
as viperfish. DISTRIBUTION
RELATED SPECIES
The family Chauliodontidae con
tains 6 species of viperfish in the
single genus Chauliodus. Sloane's
viperfish, C. s/oani, is the largest
viperfish . C. danae, C. minimus, and
C. pammelas are other members of
the same family.
Viperfish have been found in all temperate and tropical oceans.
Sloane's viperfish prefers the richer waters away from the rela
tively barren midocean.
HOW VIPERFISH HUNT
CONSERVATION
Because they live in remote ocean depths and have no com
mercial value, viperfish are probably safe from the influence
of humans.
Left: At rest, the jaws of a viperfish are usually closed. But they can be opened wide to swallow large prey.
Left: A viperfish has a light at the tip of its mobile dorsal fin ray, which it uses to attract the attention of its fish prey.
Fish are scarce in the ocean depths, but viperfish can hunt and catch prey as large as themselves.
Below: This viperfish has caught a large fish and forced it halfway into its mouth. It holds the fish with the teeth in its palate to prevent escape. The jaws are raised upward, hinged on the front part of the backbone.
The viperfish expands its throat and
swallows the fish quickly.
During this difficult process, the viperfish 's gills are pulled downward and
backward and are exposed . Blood circulation and breathing are impeded.
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A viperfish is a threatening-looking luminous creature
that has an expandable stomach/ huge jaws/ and
long/ sharp teeth. This typical predator of the ocean
depths is capable of trapping and engulfing almost
any animal it encounters in the deep/ dark seas. By
unhinging its jaws and expanding its throat/ a viperfish
can even swallow and kill prey as large as itself.
~HABITAT Light cannot penetrate ocean
waters below a certain depth. The different colors of the spec
trum that make up white sunlight are filtered out at different
rates as they pass through the dense salt water. Red light waves are absorbed first, fol
lowed by the oranges, yellows,
and greens until, at about 650 feet below the surface, only the blue light remains.
The blue twilight gets dimmer with increasing depth and fades
completely at about 3,000 feet in the clearest water. Below this
depth, all is inky darkness. Viperfish inhabit the blue twi-
light area. Fish are very scarce
at these depths because there is little for them to feed on. All
life ultimately depends on the plankton (tiny plants and ani- '
mals) that drift down from the higher depths.
At night the plankton move
upward to feed on organisms that live on the water surface. They are followed by small
deep-water fish, such as bristlemouths, that prey on them.
These fish return to the ocean depths at dawn, their stomachs
full of plankton, and are then eaten in turn by larger predators like viperfish.
DID YOU KNOW? • A viperfish's eyes are believed to be up to 30 times more sensitive to dim light
than a human's eyes.
• More than 98 percent of the energy that is fed to a viperfish's luminous organs
is converted to light. A domestic light blub converts
~ BREEDING Although divers have observed viperfish from deep-water submersible crafts, the breeding
behavior and other habits of these fish remain a mystery. It
is likely that viperfish produce large quantities of eggs that hatch into tiny larvae before
developing into adults.
Left: A viperfish can use the "bait" on the end of its dorsal fin ray to lure fish.
Right: A viperfish's body is covered with a thick, watery layer enclosed by a thin skin.
only three percent of the electrical energy into light.
• If touched, a viperfish's body is lit by pulses of light.
• A viperfish's light organs are modified glands. Sloane's
viperfish has over 1,500
compound light organs on its body.
rr~~ . ~ SPECIAL ADAPTATIONS Most fish that live in the dimly
lit deep ocean waters have
luminous organs. A viperfish has lights around its eyes, a bright fin ray lure, and rows of
photophores (glowing organs) along its flanks and belly that
give off a subdued blue glow.
~ FOOD & HUNTING Viperfish hunt mainly by sight,
relying on their big eyes to pick up the movements of fish
that swim through the deepsea gloom. Each eye has a
light-producing organ directly beneath it that shines upward
into the eye, improving its sensitivity to light. Other light or
gans above and in front of the eyes act as spotlights, shining
on the prey as the viperfish moves in for the kill.
Active hunting is one way
to find prey. But in the ocean
Left: Viperfish sometimes catch large prey but more often kill small hatchetfish.
This light matches the glim
mer of blue light that filters down from the surface, so a viperfish does not cast a shad
ow on the water below. This "camouflage" conceals it from
larger predators approaching
from the depths below.
depths, where food is scarce, a viperfish makes use of anoth
er method as well. The second ray of its dorsal fin is very long,
with a bright lure on the tip. A viperfish rests in the water
with the lure dangling in front of its mouth to attract poten
tial victims. When a fish is caught in a
viperfish's mouth, there is no escape. The stiletto-shaped
teeth of the upper jaw are designed to stab prey and hold
it fast. A viperfish can open its mouth wide and unhinge the lower jaw from the body to
accommodate large prey.
TETRA
... CLASS ~ Osteichthyes
ORDER Charociformes
FAMILY Charocidae
GROUP 4: FISH
Tetras are small freshwater fish that feed in large schools, mainly in the slow-flowing, silted rivers of Central and South America.
Some of these fish glow with iridescent color.
KEY FACTS
SIZE
Length: Mostly 1 ~-2~ in ., but the
glass tetra grows to 8 in.
BREEDING
Sexual maturity: 1-2 years.
Eggs: 100-300, laid in batches.
Hatching time: 1 -5 days.
LIFESTYLE
Habit: Found in schools in midwater.
Diet: Varied. Eat small animals, in
sects, carrion, and plant matter.
Lifespan: 3-4 years.
RELATED SPECIES
The 841 fish species in the family
Charocidae are found in Central and
South America and Africa. Relatives
include the flying hatchetfish of the
family Gasteropelecidae and the pi
ranha, Serrosalmus nattereri. Also
related is the family Lebiasinidae,
which includes the tube-mouth
pencil fish.
Range of tetras.
DISTRIBUTION
Most tetra species are found in the rivers of Central and South
America, but a few species live in Africa.
CONSERVATION
Although tetras are popular aquarium fish, captive breeding
fulfills most of the demand and keeps collection from the wild
to a minimum in most cases. Tetras that are less easy to breed
in captivity are at greater risk.
BREEDING HABITS OF THE SPLASHING TETRA ~ ,
Leaps up to lay her eggs on a low leaf, where they are safe from predators. The sticky eggs adhere to the leaf by surface tension.
3. Male: Remains near the eggs, continually leaping up to splash them with water and keep them moist until they hatch.
© MCMXCII IMP BV/IMP INC WILDLIFE FACT FILETM
2. Male: Leaps up to shed sperm on the eggs, fertilizing them. The male may fertilize up to 200 eggs in this way.
4. Young: Hatch after 3 days and drop i.nto the water. The male's parental duties are then over.
PRINTED IN U.S.A. 0160200561 PACKET 56
Tetras are small, tropical relatives of the carp that
were once classified in the genus Tetragonopterus.
Although scientists no longer use this genus name,
these freshwater fish are still popularly referred to
by an abbreviated version of this term-tetra.
Because of their vivid colors, tetras are popular
in aquariums, and they breed well in captivity.
~COlORATION Many tetras are so vividly col-ored that it is hard to imagine how they survive in the wild.
The cardinal tetra, for example,
has bright red flanks topped by a broad streak of electric blue
that extends from head to tail. The diamond tetra sparkles with iridescent green and gold,
while the glowlight tetra appears to have a red-hot rod running down its translucent
green body. These dramatic colors have
a function. In the tropical rivers and lakes where most tetras
are found, the waters may be
colored green by microscopic
plants, milky white by clay particles, or deep brown by the peat formed from decomposing forest leaves. Visibility is fre
quently poor, and the tetras' bright colors act as navigation lights, enabling individuals to
stay in contact with each other. Rather than exposing the fish
to danger, the glittering colors may help protect them by bringing them together and providing safety in numbers.
Right: The neon tetra gets its name from the luminous stripes that line its sides.
~ FOOD &: FEEDING Tetras live in loose schools among plants in the middle layer of still or slow-flowing water. Although some tetra
species eat only plant matter, most tetras are omnivorous
opportunists-eating anything small and edible that does not devour it first.
In the tropical rivers where
they live, tetras find a rich supply of food . In addition to plant matter, they eat insect larvae and worms from the river bot-
Left: In the wild the young black tetra is social, but it becomes more solitary with age.
tom and insects from the surface. They even eat animals that are caught in rising floodwaters.
Tetras' readiness to consume
almost anything can produce problems with captive fish. Many species kept in captivity even devour their own eggs and young . It is not known
whether this happens in the wild, but the tendency is probably exaggerated in an aquari
um, where there is often no other food available.
Right: Because tetras have a very wide food base, they rarely go hungry.
Left: The Congo tetra is one of the few species found in Africa. Tetras are of great interest to biologists because they adapt readily to new conditions and habitats.
DID YOU KNOW? • The cave characin is a completely blind tetra that lives in underground streams in Mexico. It uses its senses of
smell and touch to find its way around.
• Wild tetras are hardly ever caught for the pet trade be
cause the popular species breed well in captivity.
~ BREEDING Some male tetras become very animated during the breeding season. A male black tetra, for
example, circles a female with his fins spread out. He zigzags in front and drives her in and
out of vegetation. Most female tetras scatter their
eggs at random in batches of a
dozen. The transparent, slightly sticky eggs cling to plants. After laying several batches of eggs, the female abandons them. The
male smothers the eggs with sperm to fertilize them, and they hatch in two or three days. The hatchlings feed on micro-
• The brilliant colors of many tetras are "interference colors" caused by refraction of light. When the fish moves out of
the light, the colors blink off, so the fish blends into its back
ground. The bright reds of the cardinal and neon tetras, on the other hand, are caused
by pigment.
scopic water plants and animals. The splashing tetra has more
unusual breeding habits. By
laying its eggs on plant leaves hanging over the water, this species may reduce the risk of
its eggs being eaten before they hatch. The female leaps out of the water and clings briefly to the leaf while shed
ding her eggs. The male follows suit to fertilize them. The
male then sprays the eggs with water in order to keep them damp. When the eggs hatch, the young fish fall into the water and swim away.
~ CARD 37
REEF SHARK \(~ ___________________________________ G_R_O_U_P_4_:_F_IS_H __ ~
CLASS ~ Chondrichthyes ORDER Pleurotremata
FAMILY Carcharhinidae
Moving stealthily through tropical coral reefs, reef sharks are highly efficient killers. These creatures have little to fear except larger
predators of their own kind and the ever-present threat of humans.
KEY FACTS
SIZE
Length: Varies, from 5 ft. in the
black-tip reef shark to 16 ft. in the
tiger shark.
LIFESTYLE
Habit: Active predators by day
and night.
Diet: Mainly fish, crustaceans,
cuttlefish, and octopuses.
BREEDING
Sexual maturity: Approximately 2
years, depending on growth rate
and size.
Breeding season: Summer.
Gestation: 8-12 months, depend
ing on species.
No. of young: About 14; fully
formed when born.
RELATED SPECIES
There are 17 genera and approx
imately 60 species in the family
Carcharhinidae.
Range of reef sharks.
DISTRIBUTION
Reef sharks are found mainly on coral reefs in the tropics, but
some penetrate cooler, temperate waters in summer.
CONSERVATION
Sharks worldwide are threatened by sport fishing. They are also
threatened by the practice of tinning, in which the fins are cut
off for use as food, and the mutilated fish are then thrown back
into the water to die.
FEATURES OF THE BLACK-TIP REEF SHARK
Female
Dorsal fin : Has a black tip, which may be used as a social recog nition signal.
Claspers: Found in male only. Two external sexual organs, one of which is inserted into the female during mating.
Scars: On fins and rear of female's body. Caused by male biting female to grip her during mating.
©MCMXCVI IMP BV/IMP INC. WILDLIFE FACT FILETM PRINTED IN U.S.A us P 6001 12 073 PACKET 73
Reef sharks belong to the family Carcharhinidae, which
contains approximately 60 species. Most of these species
inhabit coral reefs in tropical waters. They are able to
coexist by exploiting different types of prey on separate
parts of the coral reef. Reef sharks vary widely, from the
small, fish-eating black-tip shark to the huge, fearsome
tiger shark-which has been known to kill humans.
~ HABITAT Reef sharks are usually found on
coral reefs and in nearby tropical
waters. A typical site is a shallow,
sandy lagoon with scattered cor
al formations, bounded by an
area of built-up coral known as
a "reef flat." On the seaward
side, the reef flat falls away steep
ly into deep waters, which are
linked to the lagoon by chan
nels that form the reef sharks'
access routes.
Gray reef sharks generally fre
quent the deep waters of the
outer reef slope, but they often
congregate in the channels and
use them to enter the lagoon.
The small black-tip reef shark
can swim in shallower water. It
hunts over the reef flat at high
tide, with its dorsal fin cutting
the surface. The slightly bigger
white-tip shark prefers deep gul
lies and caves, while the large
silver-tip shark usually stays on
the outer reef slope. Largest of
all is the tiger shark, which slips
into the channels from the out
er fringes to pick off large fish
including other sharks.
~ FOOD & HUNTING Reef sharks are opportunistic
feeders that eat just about any
thing, from shellfish to sea lions.
The black-tip reef shark feeds
on crabs, lobsters, cuttlefish,
and small reef fish. It hunts pri
marily at night in an area that
is familiar, ambushing its prey
among coral heads in the reef
shallows. Although the white
tip reef shark also hunts at night
for similar prey, it forages in dif
ferent waters, taking bottom
dwelling fish and octopuses from
the reef's caves and crevices.
The larger, stronger gray reef
Left: Most reef sharks inhabit tropical waters, but some species enter temperate waters.
DID YOU KNOW? • Reef sharks are highly devel-
oped at birth. One infant bit a
scientist as he removed it from
the dying mother's womb.
• Although reef sharks are dangerous, they can be sur
prisingly tame. Several have
been trained to take fish from
divers without biting them.
• Although reef sharks are re-
shark hunts for bigger prey in
deep water by night and day.
The silver-tip hunts similar prey
at similar depths, which may
partly explain why the gray reef
shark is so aggressively territori
al. The gray reef shark warns
intruders by twisting its body,
raising its snout, and dropping
its pectoral fins. It finally attacks
with slashing bites that are not
part of its normal feeding meth
od. It can even drive off the 16-
foot tiger shark, which can kill a
gray reef shark and then swal
low it whole.
Right: Reef sharks often feed in groups and may participate in "feeding frenzies. "
garded as voracious feeders,
they can actually go for days
without eating. The sharks
convert energy so efficiently
that they can get by on rela
tively little food.
• Reef sharks locate prey by detecting tiny electrical signals
that are generated by their vic
tim's nervous system.
Reef sharks breed in summer.
After following a female's scent
trail through water, the male
grips her body or fin with his
teeth, usually wounding her
despite her thick skin. He then
inserts one of two elongated
claspers (sexual organs) into
her cloaca (genital opening).
The clasper acts as a guide for
the sperm, which is passed into
a special sac within the female
Left: Reef sharks give birth to live young that are perfect miniatures of their parents.
Left: Small fish called remoras sometimes "hitch a ride" on reef sharks. The remoras use suckerlike disks on their heads to attach themselves to the reef sharks.
and stored for several months
before fertilizing her eggs the
following spring .
Like infant mammals, the
unborn sharks are connected
to the mother's bloodstream
by an umbilical cord and pla
centa. This enables them to
absorb nutrients during the 8-
to 12-month gestation period .
Unlike other fish, whose off
spring are born from eggs that
hatch in water, the female shark
gives birth to relatively few well
formed, live young.
BUTTERFLY FISH
ORDER Perciformes
FAMILY Chaetodontidae
GROUP 4: FISH GENERA Chaetodon, Forcipiger, etc.
Butterfly fish are brightly colored relatives of angelfish. They live in shallow tropical seas, where they feed on the small
animals that live in or near coral reefs.
KEY FACTS ______________________________________________________ -J
SIZE
Length: 2-8 in., depending on
the species.
BREEDING
Eggs: Laid in large batches. Young
are cared for by both parents until
independent.
LIFESTYLE
Habit: Live in reefs . Swim in pairs
or small groups. Active mostly dur
ing the day.
Diet: Mainly coral polyps. Also
small marine creatures such as
worms, sea slugs, and bottom
dwelling shrimp.
Lifespan: Several years in captivity;
unknown in the wild.
RELATED SPECIES
Butterfly fish are so closely related
to angelfish that-until recently
they were classed in the same fam
ily. An angelfish has a spine on its
gill cover, which is lacking in a but
terfly fish .
~.
• Range of butterfly fish .
DISTRIBUTION
Found in coral reefs bordering tropical seas and oceans, includ
ing parts of the Pacific, Indian, and Atlantic oceans; the Carib
bean; the Arabian Sea; and the Bay of Bengal.
CONSERVATION
Like all reef animals, butterfly fish are threatened by pollution
and damage to coral reefs. Local populations of some species
may be affected by overcollection for the aquarium trade.
FEATURES OF BUTTERFLY FISH
Eyespot: A common marking in many species. It mimics the fish 's eye and tricks a predator into attacking the tail fin instead of the vulnerable head .
Mouth: Varies depending on the species. Some have long, pipelike jaws for plucking food from coral crevices. Others have shorter, beaklike jaws for grazing on coral polyps.
©MCMXCIV IMP BV/IMP INC WILDLIFE FACT FILETM
Spines: Very sharp, lining the dorsal fin . They may deter a predator from eating the fish .
long-nosed butterfly fish,
Forcipiger f/avissimus
PRINTED IN U.S.A.
Color and pattern: Each species, and possibly each individual, has its own special markings. The stripes and spots conceal the fish 's body outline from predators and help it recognize other butterfly fish .
US P 6001 12067 PACKET 67
There are more than a hundred species of
butterfly fish in the world's warm oceans. Famous
for their vibrant colors, they are frequently displayed
in aquariums. With their deep, narrow bodies, these
fish look like butterflies at rest with closed wings. As
they dart from one coral branch to another, they
resemble butterflies flitting among flowers.
~ HABITAT Butterfly fish live in coral reefs
in the sunlit, shallow seas near
the equator. The tropical reefs
offer shelter to sea anemones,
worms, sponges, shellfish, and
starfish. The surrounding wa
ters are thick with plant and
animal plankton, providing
food for many species of fish.
These fish are in turn eaten by
Right: A butterfly fish is protected from predators by the pin-sharp spines on its dorsal fin and by the speed with which it darts outof danger.
larger predators such as bass
and groupers.
The vividness of butterfly fish
fits into the brilliantly colored
coral environment. These fish
have striking body patterns
that help break up their out
lines and at the same time
serve as identification "flags"
to their mates.
~ BREEDING In preparation for spawning, a
pair of butterfly fish cleans the
debris from a flat rock. The fe
male then lays her eggs on the
cleaned rock, and the male im
mediately swims over them,
producing clouds of sperm to
fertilize the eggs. Both fish stay with the eggs
until they hatch in about four
to eight days. After hatching,
Left: The saddled butterfly fish inhabits the coastal reefs of Australia and Central America.
DID YOU KNOW? • A butterfly fish known as the wimplefish is a "cleaner,"
nibbling parasites and dead
skin from other fish. Even a
dangerous predator stays still
to let this fish clean its body.
• The four-eyed butterfly fish fools predators with the eye
like spots above its tail, which
make it hard to tell front from
the fry (young) sink to the sea
bed, where both parents pro
tect them until they can swim
and feed themselves.
The long, slim fry look very
different from their parents.
Each finds a shelter under a
rock or plant and protects the
surrounding area. In three or
four months, it develops into
the adult form.
Right: In many butterfly fish species, an eyespot near the tail helps confuse predators.
back. To increase the confu
sion, the fish first swims slow
ly backward and then darts
forward at high speed.
• Some species, such as the ornate butterfly fish, can ad
just their body coloration at
night. This ability may allow a
breeding pair to identify each
other 24 hours a day. ----1
~ FOOD &: FEEDING Butterfly fish graze on coral
polyps. They also eat small sea
creatures in the reef's crevices.
Some species, such as the sun
burst butterfly fish, have short
jaws and flat, grinding teeth to
bite through the coral skeleton
and devour the coral polyps. In
contrast, the forceps fish has
long, beaklike jaws and very
sharp teeth. It bites off single
polyps or plucks small animals
from their hiding places. Most adults feed alone or in
small groups. Each group has its
own feeding ground. To warn
other fish away, males flash their
colorful fins. Only the forceps
fish fights intruders, raking them
with its sharp dorsal spine.
". BUTTERFLY FISH ""lIIIIII &MAN
Butterfly fish are so popular in
aquariums that every known
species has a common name,
usually describing its appear
ance. The sunburst, for exam
ple, is colored orangish gold,
while the yellow long-nose has
very long jaws.
It is possible to nurture living
coral polyps in an aquarium to
provide captive butterfly fish
with their natural food. But
there is disagreement about
whether people should take
butterfly fish from their natural
habitat, where they may be vital to the coral reef food chain.
Left: 5addle markings and eye stripes camouflage this butterfly fish by breaking up its outline.
EUROPEAN MINNOW
ORDER Cypriniformes
FAMILY Cyprinidae
GENUS fit: SPECIES Phoxinus phoxinus
The European minnow is a tiny relative of the carp. This adaptable little fish can live in almost any fresh, clean water,
and it eats almost everything it can catch.
KEY· FACTS
SIZE Length: 3-4 in. Occasionally grows up to 5~ in. The female is bigger than the male.
BREEDING Sexual maturity: 1-2 years. Spawning season: April to July. No. of eggs: Up to 1,000. Hatching: 5-1 0 days.
LIFESTYLE Habit: Sociable. Forms schools in shallow, clear water. Diet: Aquatic invertebrates such as worms, insect larvae, and crustaceans. Also flying insects and some plant matter.
RELATED SPECIES There are 2 closely related species in northern Europe: the swamp minnow and the Poznan minnow. Other members of the large family Cyprinidae include the goldfish, Carassius auratus.
Range of the European minnow. --------DISTRIBUTION The European minnow is found in most of Europe, and its range extends across northern Asia to the Bering Sea. It is not, however, found in Arctic regions.
CONSERVATION Although still common in much of its range, the European minnow suffers badly from the effects of pollution. It has disappeared from many lowland rivers.
FEATURES OF THE EUROPEAN MINNOW
Coloration: Variable. Back and sides are often deep olive green with a metallic bronze sheen on the sides blending into a pale yellow or whitish belly.
Male: Becomes flushed with red during the spawning season and develops white bumps on his head.
Female: Characterized by a deep, fat belly full of eggs during the spawning season .
Senses: The minnow picks up vibrations through lines
that run the length of its
body.
Eggs: Small, pale yellow, and covered with mucus. The female lays up to 1,000 eggs in small clumps on the
riverbed, where they stick to gravel , stones, or aquatic plants. The eggs are fertilized by the male, and they
hatch after about a week.
c; o <0 a.. (J) ::J
The European minnow is an important link in the food
chain of lakes and rivers. This small fish consumes huge
quantities of a wide range of aquatic insects and other
small creatures. In turn it is preyed upon by a variety of
larger fish as well as birds. Occasionally the European
minnow is even eaten by swamp spiders as well as by
carnivorous insects such as the great diving beetle.
~ HABITS The European minnow is com
mon in clean, fresh waters in
much of Europe and northern
Asia. It is most numerous in the
fast-flowing upper levels of riv
ers. It also lives in lakes or ponds
if the water is not too muddy and
there is plenty to eat.
The European minnow is an
easy catch for various predatory
fish and fish-eating birds. Occa
sionally it is also preyed upon by
carnivorous insects. Its main de
fenses are its agility and instinc
tive avoidance of the open-water
hunting areas of larger fish . Stay
ing in shallower water, it takes
cover in plants near the banks.
In summer European min
nows gather in schools of up to
a hundred to feed near the sur
face. They often swim with oth
er small fish, such as young dace,
bleak, and roach. Schools offer
safety in numbers, but in winter
they break up and each minnow
moves closer to the riverbed.
Relying on its dark, mottled col
oring for camouflage, the min
now swims close to the bottom.
It hides under stones when the
river swells with heavy rain and
powerful currents threaten to
sweep it away.
~ FOOD &: FEEDING Like most fish that live in a vari
ety of waters, the European min
now is adaptable, eating almost
anything that it finds. Although
it may nibble on water plants
and eat algae growing on stones
or plant stems, it prefers to feed
on small animals.
The minnow preys mainly on
freshwater shrimps, worms, and
the aquatic larvae of insects like
the caddis fly, mayfly, and mos
quito. But it attacks other small
creatures it comes across, even
left: The European minnow favors clean, oxygen-rich waters, which provide plenty of food.
DID YOU KNOW? • A European minnow alters
its coloring according to its
mood. When alarmed, it may
become almost colorless.
• In medieval Europe, min
nows were caught for food
and were so prized that they
were served at state banquets.
In some parts of Europe they
are still caught for food.
leaping from the water to seize
an insect from the air.
Like other members of the
carp family, the European min
now has no teeth. Instead, it has
special nodules on the bones at
the back of its gill chamber. The
minnow uses them to grind its
food against a horny pad . Each
species within the family has a
different arrangement of these
"teeth." They are often the only
reliable way to distinguish be
tween similar carp species.
Right: The European minnow has a flexible pair of jaws that it thrusts forward when feeding.
• After an absence of many
years, minnows returned to
London's Thames River in the
1970s, showing that the water
had become cleaner.
• The European minnow is a
favorite prey of the European
kingfisher. It is exposed to at
tack from above because it
feeds near the surface.
I, ,,~j NATUREWATCH The European minnow can
be caught with a net in streams
and ponds. Its mottled dark
olive back makes it easy to
recognize, but there are some
color variations. A minnow
living in cloudy water is paler
and less strongly patterned
~ BREEDING The European minnow is usually
a drab color with a dark green,
blotchy back and a silvery belly.
But in the breeding season the
male's belly becomes flushed
with red and he develops a rash
of hard, conical white bumps
on his head. At the same time
the female's belly swells with
eggs. The sexes mingle in a
large school before pairing and
spawning at the river bottom.
As the small mucus-covered
eggs are laid, they stick to the
left: An injured minnow releases chemicals that warn the rest of the school to scatter.
than one in a clear stream.
In summer minnows can
often be seen in large schools
near the surface in shallow
river waters . Because these
fish live only in clean water,
their presence indicates that
the river is not polluted .
rocks in clumps. The male fertil
izes them, and they hatch in five
to ten days. The warmer the wa
ter, the faster the eggs develop.
Each newly hatched fish stays
among the stones at first. It lives
off the contents of the yolk sac
attached to its stomach. When
that is gone, the minnow has to
find its own food . It eats tiny
microorganisms that float in the
water until it is big enough to
tackle insects and worms.
If conditions are right, the min
now grows quickly enough to
breed within a year. But many
take two years to mature.
BLENNY ",CARD 40
GROUP 4: FISH " ~ " ~ ORDER Perciformes
FAMILY Blenniidae
GENERA Various
There are hundreds of species of blennies. All of these species are found in shallow coastal waters in the temperate and tropical parts of the Atlantic, Pacific, and Indian oceans.
KEY FACTS
SIZE
Length: Varies. Can measure up
to 12 in.
BREEDING
Sexual maturity: 1 year.
Spawning: Varies depending on
the species.
No. of eggs: Varies depending on
the maturity of the fish.
Hatching period: Varies depending
on the species.
~ LIFESTYLE
Habit: Territorial. Individual guards
home range.
Diet: Barnacles, small crustaceans,
some algae and seaweed.
Lifespan: Up to 4 years.
RELATED SPECIES
There are more than 275 species in
the family Blenniidae.
FEATURES OF BlENNIES
© MCMXCII IMP BV/IMP INC WILDLIFE FACT FILETM
Range of blennies.
DISTRIBUTION
Blennies are found in shallow water in tropical and temperate
parts of the Atlantic, Pacific, and Indian oceans.
CONSERVATION
Blennies are not currently in danger. But because they live in
coastal waters, they are more susceptible to pollution than
open-sea fish.
Eggs: Female lays batch in debris or hole. Male fans eggs with fins to oxygenate them.
PRINTED IN U.S.A.
Coloration: Many blennies change color for various reasons. Defense, aggression, submission, breeding, and spawning can cause color changes. Blennies also use color changes for camouflage.
0160200591 PACKET 59
Blennies can be found in rock pools
around coastlines. They have many enemies
that prey on them when the rock pools are shallow
and exposed at low tide. As a result, these small fish
have developed a variety of tactics for defense.
~ HABITAT Because they live in shallow water, blennies must cope with the tides and extremes of temperature. When exposed to the sun, the water in a rock pool can become very hot. In cold waters, the temperature can drop to freezing. Rain trapped in rock pools can change the salt content of the water, and blennies must make biological changes to counteract the effects.
Blennies have many enemies and several ways of coping with them. Some species, such as the shanny, change color in order to camouflage themselves against their background. Other species hide in crevices or under rocks. Still other species, such as the tompot bien ny, hide in kelp and seaweed.
~ BREEDING Most North Atlantic blennies spawn between April and August. The male fertilizes the eggs, which are rarely larger than the head of a pin. The eggs are usually laid under stones and rocks but may sometimes be hidden in discarded receptacles such as bottles or cans.
After laying the eggs, the female abandons them. The male guards the eggs and fans them with his pectoral fins to make sure they get enough oxygen. The young fish, called f'Yt are very vulnerable, and many are eaten by predators.
The eel pout, which is related to blennies, gives birth to between 20 and 300 live young, depending on the female's size. The eggs hatch inside the fe-
~ FOOD &: FEEDING The majority of blennies are territorial. They feed within a certain area, which they guard against other blennies. Some blenny species have tiny teeth and nibble the limbs of barnacles. Other species have pow-
left: The viviparous blenny gives birth to already hatched young.
Right: Many species of blenny can "haul out" on the rocks.
Far right: The jewel-like diamond blenny lurks in the waving tentacles of an anemone.
male's body after about three weeks, but it is four months before the young are born. As a result of this delay, the newborn fry are well developed and have a better chance of surviving.
erful, curved teeth and attack fish larger than themselves.
Blennies also eat tiny crabs, bristleworms, and other small shellfish, as well as seaweed. In aquariums, they are fed worms and small pieces of meat.
Above: The male sabre-toothed blenny stays with the developing eggs and guards them.
Above right: Yarrell's blenny is one of many species that have the branched tentacles shown here.
DID YOU KNOW? • Some blennies can leave the water to rest on rocks or escape from predators. • Blennies dig shelters under rocks by wriggling their bodies in the sand.
[- ,-] NATUREWATCH Blennies move very quickly. If you move a stone in a rock pool, you may see a blenny dart out to find another hiding place. Blennies are very wary of overhead shadows, and they will quickly notice
• A blenny's eyes move independently of each other, so it can see predators both in and above the water. • Blennies of the genus Runu-10 may bite swimmers.
your presence. Some blennies are bold enough to venture into open water.
If you can catch a blenny in a glass jar, you will be able to study it in detail. But be sure to return the fish to its pool.