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© 2006 Thomson-Brooks Cole Chapter 10 Fishes

© 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

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Page 1: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Chapter 10

Fishes

Page 2: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Key Concepts

• Hagfishes and lampreys are jawless fishes.

• Sharks, skates, and rays have skeletons composed entirely of cartilage.

• Sharks have streamlined bodies and highly developed senses that help them to be efficient predators.

• Most marine fishes have skeletons composed primarily of bone.

Page 3: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Key Concepts

• The shape of a fish’s body is primarily determined by the characteristics of its environment.

• Many fishes exhibit coloration and color patterns that help them blend in with their environment.

• Color in fishes functions in camouflage, species recognition, and communication.

Page 4: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Key Concepts

• Most bony fishes have a swim bladder that helps them maintain neutral buoyancy.

• Most marine fishes are carnivorous, but herbivores, omnivores, and filter feeders also exist.

• Most marine fishes are oviparous and produce large numbers of eggs.

• Fishes such as salmon and eels migrate long distances sometime during their life cycle.

Page 5: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Fishes

• Fishes are vertebrates—animals that possess vertebrae, a series of bones or cartilages that surround the spinal cord and help support the body

• Primitive fishes lacked paired fins and jaws

• Adaptation of jaws and paired fins allowed fish to more efficiently obtain food

Page 6: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Jawless Fishes

• Class Myxini (hagfish) and class Cephalospidomorphi (lampreys)

• Lack both jaws and paired appendages• Have skeletons of cartilage (no bone)• Lack scales• Hagfish also lack vertebrae (some

scientists consider them invertebrates)

Page 7: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Hagfishes

• Bottom dwelling “slime eels”• Skins are used to make leather goods• Hagfish feeding apparatus is composed

of two dental plates containing horny cusps, used to grasp the prey’s flesh– feed on live prey and scavenge

• Slime glands produce abundant milky, gelatinous fluid if hagfish is disturbed

• Sexes are normally separate

Page 8: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 9: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Lampreys

• Have oral disk and rasping tongue covered with tooth-like keratin plates

• Reproduction– males migrate up rivers and build nests– females arrive and they spawn; eggs

attach to stones of the nest– larvae are benthic filter feeders– after 3-7 years, they metamorphose into

adults and return to the sea

Page 10: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Cartilaginous Fishes

• Class Chondrichthyes– e.g. sharks, skates, rays, chimaeras

• Skeleton of cartilage• Possess jaws and paired fins• Have placoid scales• 2 major groups:

– holocephalans (chimaeras or ratfish)– elasmobranchs (2 body forms: streamlined

or dorsoventrally flattened)

Page 11: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Sharks

• Excellent swimmers with streamlined bodies– swim with powerful, sideways sweeps of

the caudal fin (tail)– heterocercal tail—caudal fin in which the

dorsal lobe is longer than the ventral

• Males have claspers—modified pelvic fins which transfer sperm from the male to the female

Page 12: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 13: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Sharks

• Maintaining buoyancy– sharks sink if they stop swimming– large livers produce squalene—an oily

material with a density less than seawater– squalene offsets the shark’s higher density

to help maintain buoyancy

Page 14: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Shark Sensory Systems

• Vision– a clear nictitating membrane covers and

protects each lidless eye– many species seem to have color vision

• Olfaction– more important than vision – almost 2/3 of

the shark’s brain cells are involved in processing olfactory information

– sharks are sometimes referred to as “swimming noses”

Page 15: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Shark Sensory Systems

• Lateral line system– consists of canals running the length of

the animal’s body and over the head– canals open to the outside at regular

intervals, allowing free movement of water over the neuromasts (sensory receptors) within

– neuromasts detect vibrations in the fluid which alert the shark to movements in the water, possibly made by prey animals

Page 16: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 17: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Shark Sensory Systems

• Ampullae of Lorenzini– organs scattered over the top and sides of

the animal’s head – sense electrical currents in the water

Page 18: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Digestion in Sharks

• Blade-like, triangular teeth in the mouth grasp prey and tear off chunks

• Food is swallowed whole (sharks cannot move their jaws back and forth to chew)

• Food passes through stomach to a short intestine containing a spiral valve– spiral valve—a structure which aids in

absorption by slowing the movement of food and increasing the surface area

Page 19: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Osmoregulation in Sharks

• Maintain an internal solute concentration > or = to the seawater– retain large amounts of nitrogenous

wastes, mostly urea and trimethylamine oxide (TMAO)

• Gills and rectal gland (a large structure that empties into the intestine) work to excrete excess sodium chloride

• Kidney excretes other salts

Page 20: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Reproduction in Sharks

• Sperm produced in paired testes are transferred to the female through grooves in the claspers

• Oviparity– most primitive mode– eggs are laid outside the body and the

embryos develop in a protective case– e.g. whale sharks, bullhead sharks

Page 21: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Reproduction in Sharks

• Ovoviviparity– most common mode– eggs hatch within the mother’s uterus but

no placental connection is formed• young are nourished by yolk from the egg

– e.g. basking sharks, thresher sharks, saw sharks, sand tiger

Page 22: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Reproduction in Sharks

• Viviparity– most recent mode to evolve– either the young directly attach to the

mother’s uterine wall or the mother’s uterus produces “uterine milk” that is absorbed by the embryo

– e.g. requiem sharks, hammerhead sharks

Page 23: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Skates and Rays

• Have flattened bodies adapted to a bottom existence

• Greatly enlarged pectoral fins that attach to the head

• Reduced dorsal and caudal fins• Eyes and spiracles (openings for the

passage of water) on top of the head• Gill slits on the ventral side• Specialized pavement-like teeth are

used to crush prey (e.g. invertebrates)

Page 24: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Differences between Skates and Rays

Rays: swim by moving fins up and down

Skates: create a wave from the forward to backward fin edges

streamlined tails with venomous barbs or spines

fleshier tails with small fins and no spines

larger size smaller size

ovoviviparous mostly oviparous

Page 25: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 26: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Defense Mechanisms

• Electric rays have electric organs that can deliver up to 220 V

• Stingrays have hollow barbs connected to poison glands– treatment for stingray wounds: submerge

in hot water to break down protein toxin

• Sawfishes and guitarfishes have a series of (non-venomous) barbs along their pointed rostrums

Page 27: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Chimaeras

• Subclass Holocephali– e.g. ratfish, rabbitfish, spookfish

• Large pointed heads and long, slender tails

• Gills covered by operculum; water inhaled through the nostrils

• Males have claspers on their heads and pelvic fins

Page 28: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Chimaeras

• Oviparous – produce large eggs in a leathery case

• Have flat plates for crushing prey instead of teeth

• Generally bottom dwellers• Little commercial value

– marketed as food in parts of China and New Zealand

– their oils can be used as a lubricant

Page 29: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Bony Fishes

• Class Osteichthyes• Very diverse 25,000 species• Most forms have: swim bladder (or

lung), bone, bony scales, and fin rays• 2 major lineages:

– lobefins (subclass Sarcopterygii) – coelacanths, freshwater lungfish

– ray-finned fishes (subclass Actinopterygii)

Page 30: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Coelacanths

• Characterized by lungs and lobed, paired fins resembling tetrapod limbs

• Known from fossils only before live specimen was discovered in 1938

• Skeletons are bone + cartilage• Fat-filled swim bladder for buoyancy• Nearly isotonic to seawater like sharks• Ovoviviparous

Page 31: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Ray-Finned Fishes

• 2 major groups:– subclass Chondrostei – primitive forms

with heterocercal tails, primarily cartilage skeleton, ganoid scales• ganoid scales—thick, heavy scales which give

the fish an armored appearance

Page 32: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 33: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Ray-Finned Fishes

– subclass Neopterygii – homocercal tails, cycloid or ctenoid scales, more maneuverable fins• homocercal tails—tails with dorsal and ventral

flanges nearly equal in size; vertebral column usually does not continue into the tail

• cycloid & ctenoid scales—scales that are thinner and more flexible; less cumbersome for active swimmers

Page 34: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 35: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 36: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Ray-Finned Fishes

• Possess unpaired median fins and paired fins, providing better control of movements

• Median fins consist of 1 or more dorsal fins, caudal fin, and usually anal fin– help maintain stability while swimming

• Paired fins consist of pectoral and pelvic fins– both used in steering– pectoral fins also help to stabilize the fish

Page 37: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 38: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 39: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 40: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Body Shape

• Fusiform body shape—streamlined shape with a very high and narrow tail– efficient movement for active swimmers

Page 41: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Body Shape

• Laterally compressed or deep body– allows

navigation through grass or corals

Page 42: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Body Shape

• Depressed or flattened bodies– bottom-dwelling fishes

Page 43: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Body Shape

• Globular bodies, enlarged pectoral fins– appropriate for sedentary lifestyle

Page 44: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Body Shape

• Long, snake-like bodies, absent or reduced pelvic and pectoral fins– useful for burrowing, living in tight spaces

Page 45: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Fish Coloration

• 2 basic types of fish colors:– pigments (biochromes)– structural colors

• Pigments—colored compounds found in chromatophores – chromatophores—irregularly-shaped cells,

usually appearing as a central cell body with radiating processes

– fish can alter color by moving pigments between the central core and processes

Page 46: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Fish Coloration

• Structural colors—colors produced by light reflecting from crystals located in specialized chromatophores– iridophores—chromatophores used to

produce structural colors– colorless, relatively immobile crystals

produce mirror-like silver or iridescence

Page 47: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Fish Coloration

• Countershading is seen in open ocean fish– obliterative countershading—coloration in

which the back (dorsum) is dark green, dark blue or gray, and the shades grauate on the sides to the belly’s pure white

• Disruptive coloration—background color of the body is usually interrupted by vertical lines; may be an eyespot– more difficult for predators to see the fish

Page 48: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 49: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Fish Coloration

• Cryptic coloration—coloration which blends with the environment– used for camouflage

Page 50: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 51: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Fish Coloration

• Poster colors—bright, showy color patterns– may advertise territorial ownership, aid

foraging individuals to keep in contact, or be important in sexual displays

– aposematic (warning) coloration—bright coloration to warn predators that the fish is too venomous or spiny to eat

Page 52: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 53: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Locomotion in Bony Fishes

• In swimming, the trunk muscles propel the fish through the water– trunk muscles are arranged in a series of

muscle bands– muscles contract alternately from one side

of the body to the other– contractions originate at the anterior end

and move toward the tail, flexing the body and pushing against the water

Page 54: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 55: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Locomotion in Bony Fishes

• Fish with different body forms swim in different ways– elongate fish undulate the entire body– swift swimmers flex only the posterior

portion of the body– other fish are somewhere in between– fish with a dermal skeleton can only flex

the area before the caudal fin– some fish swim using their fins alone

Page 56: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 57: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 58: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Respiration and Osmoregulation

• Gills often used to extract O2, eliminate CO2, and aid in salt balance– gill filaments—highly vascularized, rod-like

structures which compose the gills– countercurrent multiplier system—blood

flows in the opposite direction from the incoming water, maintaining a stable gradient that favors the diffusion of O2 in and CO2 out of the body

Page 59: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 60: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 61: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Respiration and Osmoregulation

• Water must be continuously moved past the gills to keep blood oxygenated– most bony fish ventilate gills by pumping

water across them– very active fishes use ram ventilation—

continuously swimming forward at high velocity with the mouth open

Page 62: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Respiration and Osmoregulation

• Blood’s salt concentration is about 1/3 that of seawater, so water is lost

• Fish drink seawater to compensate– chloride cells—specialized cells on the gills

which eliminate most of the excess salt– kidneys and digestive tract remove other

excess salt– marine fish excrete negligible amounts of

urine in order to retain maximum water

Page 63: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 64: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Cardiovascular System

• Consists of heart, arteries, veins, and capillaries

• Path of blood:– deoxygenated blood collected from veins

by sinus venosus (thin-walled chamber)– passed to atrium, then ventricle– ventricle propels blood to gill capillaries

where it is oxygenated– collected from gills by dorsal aorta and

passed to body via arteries and capillaries

Page 65: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Cardiovascular System

• Many active swimmers have a countercurrent arrangement of blood vessels– maintains body-core temperature at 2-10o

C above seawater, increasing efficiency of swimming muscles

– heat is transferred from arteries coming from the body core to veins near the outside, so that venous blood is warmed before flowing toward the core

Page 66: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 67: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Buoyancy Regulation

• Most fish use a swim bladder—a gas-filled sac that helps offset the density of the body and regulates buoyancy– the fish can adjust the amount of gas in

the swim bladder to maintain depth– gas is added as the fish descends and

removed as it ascends

Page 68: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Buoyancy Regulation

• 2 methods for adjusting the amount of gas in the swim bladder– gulping air from the surface or spitting air

out as needed– gas gland—a specialized gland which fills

the swim bladder from gases dissolved in the blood• fish with a gas gland empty gas from the swim

bladder through diffusion into the blood

• Active swimmers do not have swim bladders, and must keep swimming

Page 69: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Nervous System and Senses

• Nervous system consists of: brain, spinal cord, peripheral nerves, and various sensory receptors

• Olfaction– olfactory pits—blind sacs opening to the

external environment that contain olfactory receptors

– size varies with dependence of fish on olfaction

Page 70: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Nervous System and Senses

• Taste and hearing– taste receptors may be located on the

surface of the head, jaws, tongue, mouth and barbels (whisker-like processes about the mouth)

– bony fishes have a lateral line system for detecting movement in the water

– ears are internal and have a detection range of 200 to 13,000 hertz• human range = 20 to 20,000 hertz

Page 71: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Nervous System and Senses

• Vision– no eyelids– usually don’t need to adjust pupil size

because of the low quantity of light– entire lens moves back and forth to focus– eyes are usually set on the sides of the

head– most have monocular vision– shallow-water species can perceive color

Page 72: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Feeding Types

• Carnivores (e.g. pufferfish, groupers)– most bony fishes are carnivores– prey are usually seized, swallowed whole

• chewing would block water flow past gills

• Herbivores (e.g. surgeonfish, parrotfish)– feed on a variety of plants and algae– teeth often broad and flat with a sharp

edge to scrape food from surfaces– may have gizzard-like stomach to grind

vegetable matter

Page 73: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 74: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Feeding Types

• Filter feeders (e.g. anchovies, larvae)– feed on plankton– typically use gill rakers—projections from

the gill arches which filter phyto- and zooplankton from seawater

– most travel in large schools, and are an important food source for larger carnivores

Page 75: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Adaptations to Avoid Predation

• Many exhibit elaborate camouflage• Pufferfishes and porcupinefish inflate

their bodies to deter predators• Flying fishes use enlarged pectoral fins

to glide through the air and escape• Pearlfish hide in other organisms• Parrotfish secrete a mucus cocoon• Surgeonfish are armed with razor-

sharp spines

Page 76: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Adaptations to Avoid Predation

• Clingfishes use a sucker to attach to rocks so predators can’t dislodge it

• Triggerfish projects spines to deter predators or wedge itself into cracks

• Scorpionfish and stonefish have venom glands for self-protection

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© 2006 Thomson-Brooks Cole

Reproduction in Bony Fishes

• Gonads are paired structures suspended from the roof of the body cavity by mesenteries (membranes)

• Sperm and eggs pass to the outside through ducts, except in salmon

• Egg and sperm development is usually seasonal

• Variation in the level of pituitary and gonadal hormones controls the reproduction process

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© 2006 Thomson-Brooks Cole

Reproduction in Bony Fishes

• Pelagic spawners (e.g. tuna, wrasses)– release vast quantities of eggs into the

water for fertilization by males– fertilized eggs drift with the currents– no parental care

• Benthic spawners (e.g. smelt)– non-buoyant eggs with large yolks– no parental care– pelagic or benthic embryos/larvae

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© 2006 Thomson-Brooks Cole

Reproduction in Bony Fishes

• Brood hiders (e.g. grunion)– species that hid their eggs in some way

but exhibit no parental care

• Guarders (e.g. damselfish)– species that care for their offspring until

they hatch and, frequently, through their larval stages

• Bearers (e.g. jawfish, seahorses)– species that incubate their eggs until they

hatch (in the mouth or a special pouch)

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© 2006 Thomson-Brooks Cole

Reproduction in Bony Fishes

• Larval development– many larvae are zooplankton– initially nourished by a yolk sac attached

to the abdomen; absorbed once mouth and digestive tract have developed

– larva grows into juvenile, leaves the planktonic community to become adult

– fishes grow for as long as they live

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© 2006 Thomson-Brooks Cole

Reproduction in Bony Fishes

• Hermaphroditism—individuals have both testes and ovaries at some time in their lives– occurs in at least 14 bony fish families– synchronous—possessing functional

gonads of both sexes at one time– sequential—changing from one sex to

another• protogyny—changing from female to male• protandry—changing from male to female

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© 2006 Thomson-Brooks Cole

Fish Migrations

• Daily migrations usually associated with feeding and predator avoidance

• Seasonal migrations usually associated with spawning, changing temperatures or feeding

• Migrations may occur within seawater or between seawater and fresh water– catadromous—fishes that move from fresh water

to seawater to spawn– anadromous—fishes that move from seawater to

fresh water to spawn

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© 2006 Thomson-Brooks Cole

Fish Migrations

• Freshwater eels– best-studied catadromous fishes– migrate down coastal rivers to the sea

during the fall– adults spawn and then die– young hatch, develop into leaf-like

leptocephalus larvae, and migrate back to rivers

– after arrival, young metamorphose into juveniles (elvers) that migrate into streams and estuaries

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© 2006 Thomson-Brooks Cole

Page 85: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 86: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Page 87: © 2006 Thomson-Brooks Cole Chapter 10 Fishes. © 2006 Thomson-Brooks Cole Key Concepts Hagfishes and lampreys are jawless fishes. Sharks, skates, and rays

© 2006 Thomson-Brooks Cole

Fish Migrations

• Salmon– Atlantic/Pacific species are anadromous– Pacific species return to spawning grounds

once, reproduce, and die; Atlantic species may spawn more than once

– lay eggs in a redd—a shallow depression in the gravel of a fresh water stream

– salmon navigate upstream by the characteristic odor of the stream; there is not agreement on how they locate the correct river’s mouth from the open sea