BIOL 1442 Ch 29 Fishes

Fishes were the earliest

vertebrates

The Agnatha have a

distinct cranium and complex sense organs

The superclass Agnatha includes

hagfishes and lampreys (jawless fishes)

The defining feature of living jawless fish are

lack of jaws and paired lateral appendages as well as the lack of internal ossification and scales

Some of the earliest jawless fish were

Ostracoderms

Haikouichthys

genus of fossilized fish found in China from 530 million years ago that have vertebrate features

The superclass Agnatha is divided into two classes:

Myxini and Petromyzontida

Myxini includes at least 70 species of _ which are

hagfish; eel-like scavengers that live on the ocean floor and feed on living or dead invertebrates, fishes, and marine mammals

Hagfish are almost ( ), but they have ( ) to help them locate food

completely blind; sensory barbels

Myxini feed by using

keratinized teeth on a movable cartilaginous plate

Myxini have unique slime glands that

produce a milky mucus that upon contact with water, becomes incredibly slippery, making the animal almost impossible to hold

Myxini have a ( ) skull and a ( ) skeleton

cartilaginous; fibrous and cartilaginous

The petromyzontida include

approximately 40 species of lampreys

Lampreys possess

extrinsic eye muscles, at least two semicircular canals, a true cerebellum, and arcualia (cartilaginous structures above the notochord)

The nervous system of petromyzontida include

dorsal tubular nerve cord, well-differentiated brain, small cerbellum, and 10 pairs of nerves

As adults, lampreys are characterized by a

rasping tongue within a toothed, funnel-like sucking mouth

many lampreys have a ( ) stage

parasitic

Petromyzontidae have the ( ) among the invertebrates

number of chromosomes (164-174)

In Petromyzontidae, eggs are fertilized

externally

Gnathostomes are

“Jaw-mouths”, vertebrates that possess true jaws

Early gnathostomes had two sets of paired fins:

pectoral fins on the anterior body and pelvic fins on the posterior body

The two early groups of gnathstomes were

acanthodians and placoderms

Modern gnathostomes include the clades

Chondrichthyes and Osteichthyes

Chondrichthyes include

Elasmobranchii (sharks, rays, skates, and sawfishes) and Holocephali (Chimaeras/ghost sharks)

Chondrichthyes are

jawed fishes that posses paired fins and a skeleton made of cartilage

Sharks have ( ) skin covered with

abrasive; tooth-like scales called placoid scales

A few species of sharks and rays are ( ) feeders

suspension

Sharks have ( ) called ampullae of Lorenzini that

electroreceptors; allow sharks to detect the electromagnetic fields that are produced by all living things

Sharks, most fishes, and aquatic and larval amphibians have

a row of sensory structures called the lateral line, which are used to detect movement and vibration in the surrounding water

Sharks have no mechanism for

maintaining neutral buoyancy

Shark reproduce ( ) and eggs are fertilized ( )

sexually; internally

Most shark species are ( ) although some can be

ovoviviparous; viviparous

In general, Chonrichthyes have a ( ) body and a ( ) tail

fusiform or dorsoventrally flattened body; heterocercal caudal

Rays and Skates can be distinguished from sharks by their

flattened bodies, pectoral fins that are large and fused to the head, and gill slits on their ventral surface

Holocephali have

a diphycercal tail, lack scales, teeth modified as grinding plates, and four pairs of gills covered by an operculum

Osteichthyes are characterized by

a bony skeleton

Osteichthyes have a ( ) skeleton with

ossified; specialized bone cells that produce and maintain a calcium phosphate matrix

Osteichthyes are consist of

skin covered by overlapping scales, glands that secrete mucus that reduces drag when swimming, swim bladder, and a lateral line system

All bony fishes use ( ) to breathe

gills

Osteichthyes can be divided into two extant clades:

Actinopterygii (ray-finned fishes) and Sarcopterygii (lobe-finned fishes)

Actinopterygii include

tuna, bass, trout, salmon, +; fan of slender bones that support their fins

Sarcopterygii fins are

fleshy and lobed