October 17, 2008. Fish Friday #4. Please read the Ah-King paper for next Monday

October 17, 2008. Fish Friday #4.

Please read the Ah-King paper for next Monday.

- switch in topics -- evolution of mating systems

today’s focus

Lanternfish - Myctophiformes

- deep sea (150-2,000 m down) --> migrate shallower at night (50m)

-- varies with species, sex, latitude, and age

Lanternfish - Myctophiformes

- photophores on head and bodies-- overlaid by modified scale which acts as lens

-- arranged in distinct groups --> species specific

-- ventral photophores act as camouflage

-- some species have photophore by head to illuminate prey

-- males and females differ in arrangement of photophores by tail

-eat crustaceans -- temperate species (where food varies) -- store fats in body and around swim bladder

- targets of fisheries off of S. Africa-- used for fish meal and fish oil

Lanternfish - Myctophiformes

Lampridiformes

- open ocean animals

- large diversity in body form

- uniting character is their jaws

-- upper jaw not connected to cheek bones & middle nasal cartilage displaced at back

-- allows jaw to be carried forward

-- one species opens mouth & increases buccal cavity by 40X

Lampridiformes - Opahs (aka Moonfish)

- bears little resemblance to others in this group- up to 2 m in length- disc shaped, laterally compressed- brilliantly colored fins and jaws

Lampridiformes - Oarfish

Oarfish (cont’d)

- longest teleosts --> up to 8m

- anterior rays of dorsal fin as“cockscomb”

- pelvic rays modified into long filaments

Oarfish (cont’d)

- maintain themselves vertically to see pelagic crustaceans against downwelling light

- may have been “sea serpent” reported by early seamen --> “head of horse with a flaming red mane”

Oarfish (cont’d)

frequently washedup on shores afterstorms

Lampridiformes - ribbon fish

similar body shape as oarfish

Polymixiformes - beardfishes

- taxonomic placement uncertain

- deep-bodied, large-eyed fishes from tropical oceans

- long pair of barbels off of chin

Paracanthopterygii

- huge group

- hole in skull through which cranial nerves pass defines the group

- pirate perch, trout perch, cavefishes, goosefishes, toadfishes, batfishes, cusk eels, brotulas, pearlfishes, cods, pollocks, haddocks, whiting, hakes, deepsea anglers, plus many, many more

Percopsiformes

- found only in N.A.

Percopsidae

troutperch

Aphredoderidae

pirateperch

Paracanthopterygii

Amblyopsidae

blind cavefish

- many species adapted to cave life-- only taxonomic group where all are cave dwellers-- 8 spp.-- one in swamps, the others in caves

Cavefish

blind cavefish

- Northern cavefish --> total darkness-- well developed lateral line-- parts of brain associated with vision are smaller than

parts with lateral line-- large pectoral fins --> “row” slowly in search of food-- slow life-style

- no predators, but no food - eat whatever drifts in- can live to 70 yrs. of age

Pirate Perch

Percopsiformes

- found in swamps

- intriguing anal opening

urogenital opening on pirate perch

- opening by anal fin asjuveniles, but “migrates”under throat as it grows into an adult

Pirate Perch

Pirate Perch

Why anus by throat?- gill brood? - one female found

with brood in mouth

- secretive - comes out of coverjust enough to poop and go back in?

answer provided in 2004.- animals brood in canals in underwater

root masses- females go in narrow canals and

release eggs -- some might spit them further inthe canal. -- helps keep eggs from falling out asthe fish backs out from the canal.

- males come in and release sperm- then guard the canals for quite some time

Ophidiiformes

big group (335 spp.)

- pectoral fins high up

-pelvic fins (when present) right under the head

Ophidiiformes - pearlfishes- live in sea cucumbers, clams, starfishes

- some just live in the host and eat stuffas it comes by

-others feed directly on the host itself

- two distinct larval stages- pelagic form - vexillifer- demersal form - tenuis

pearlfish

Ophidiiformes - cusk eels

- live very deep -- used to be deepest fish, but not any more- dorsal, caudal, and anal fin continuous- larvae occur in upper layers of water

Paracanthopterygii

Gadiformes - cods, haddock, pollocks & whitings - 482 species

commercially important group

cod used to be huge- length 1.8m, 90 kg

rarely find fish this large any more

What happened to the Atlantic cod?

Atlantic cod

Low fat

18% protein

When dry, 80% protein

By the year 1000, the Basque have a well established market in salted cod

Source of the cod a secret, but there had to be a place not only to catch, but to dry and salt the fish

By mid-late 1400s, others want in on the secret

In 1497 John Cabot “discovers” New Found Land and claims it for England

In 1535 Jacques Cartier “discovers” the St. Lawrence River and claims it for France

Claimed that "the schools of cod in the waters off Newfoundland were so thick that they slowed the ship."

Also discovered 1,000 Basque fishing vessels

Many countries continued to fish these waters for almost 500 years

“Unless the order of nature is overthrown, for centuries our fisheries will continue to be fertile” -- Canadian Minister of Agriculture, 1885

For over 200 years, 60% of the fish eaten in Europe was cod

More than one way to catch a fish…

Handlining – one baited hook

Longlining – many baited hooks

More than one way to catch a fish…

Traps and gillnets

More than one way to catch a fish…

Trawlers

Catch a lot of fish

Bottom trawls damage the benthic environment

The 1950s saw an increase in “factory-fishing” vessels from Spain, Portugal, USSR and elsewhereFish can be frozen quickly.Time to salt and dry fish no longer needed.

By 1970s, widely known that catches were declining

Canada and US pass laws in 1976-1977 to extend their national jurisdictions over marine living resources out to 200 nautical miles

Foreign fleets gone, but both US and Canada build factory-style trawlers

Government Mismanagement

• For years, scientists warned that too many fish were being taken

• Politicians did not want to take the unpopular step of closing the fishery and putting people out of work

• Argued that these fish were migratory, would show up somewhere else

Canadian government bans cod fishing in 1992

• 40,000 people out of work

• Politicians promised the ban would only last a few years, scientists argued recovery would take a decade or more

• Ban extended in 1994

• Some fishing allowed in 1999-2001

• Complete closure in 2003

Data from Hutching and Reynolds 2004BioScience 54:297-309

Stocks have not recovered

Some blame harp seals

Historically largest stock

(note differences in scales)

What are more likely reasons?

Batrachoidiformes - toadfishes and midshipmen

- low activity level -- 3 pairs of gills (3 gill arches on each side)

- sharp spines - some with venom

toadfishes & midshipman- males hide under rocks & call females to them. - 2 male morphs, 1 guarder/caller and 1 sneaker

http://www.nbb.cornell.edu/Basslab/Home/Vocalizations-Hum.html

Lophiiformes

• Goosefishes, frogfishes, batfishes, deepsea angler fishes

• First three rays of dorsal fin separated from the rest of the dorsal fin.

• First 2-3 rays acts as a lure to attract prey• Enormous mouth• Eggs are enveloped in secretion which (at

spawning) swells into a large, gelatinous mass.

Goosefishes

-broad, flattened spiny head w/ upturned eyes

-lure is slender finray

-usually matches bottom substrate

-large fish and even diving birds found in some stomachs

-Found on continental shelves and slopes of all oceans except in polar areas

frogfish

http://www.youtube.com/watch?v=d22Rm6irBaQ

http://www.youtube.com/watch?v=F8VyOuJ8Uak

frogfish

-Differ from goose in having slightlycompressed head and body.

-Lure is think and slender with a fleshy bait.

-Bumpy bodies and an extreme ability to change color makes them easily camouflaged.

-Lure is deliberate. Fish see the prey and then use their lure.

- Most are in tropical or subtropical water.

batfishes

-head and trunk is broad & flattened.

-Fin rays on head are greatly reduced.

-Lure consists of a short bone embedded in the bait.

-Shape and position of pelvic and pectoral fins are well adapted for walking on sea bottom.

-Lure might produce secretions to attract prey.

-Biology poorly known.

-Most live somewhat deep (200-1,000 m) where the light is limited.

Deepsea Anglerfishes

-

-Live in deep sea.-Lure is luminous bait.-Bacteria in bait that makes light.-Many species have light guiding mirror-like structures and tubes.-Many species known from a single or very few specimens. -Most are small (<10 cm) but some large (1m).-In all seas except Mediterranean and polar regions.

Deepsea Anglerfishes

-

-Big ones are females. They are passively floating food traps. -Leaves no energy to find males (which are sparse).-Males lack a lure and jaws that allow them to feed. -Males seek out females and hook onto them with denticles on snout and chin. -Tissues become fused and female nourishes male with her own blood supply-When ready to spawn, she sends a chemical cue that causes themale to release sperm.

Amazing Reproductive Strategy

Review Questions.

1. List 2-3 details about each of the following fishes: lanternfish, opahs, oarfish, beardfishes, pirate perch, blind cavefish, pearlfishes, cusk eels, cod, toadfishes, midshipmen, goosefishes, frogfishes, batfishes, deepsea anglerfishes.

2. Why do pirate perch have an anus right under their throats?

3. List some of the traits that blind cavefish have evolved to allow persistence in caves.

4. Explain how technological innovations helped lead to the collapse of the cod fishery.

5. Describe the mating system of the deepsea anglerfishes.