I. Fishes – Overview

B. Chondrichthyes (Cartilaginous fishes)1. Sharks

• Fusiform body• Heterocercal tail• Typically two dorsal fins• Pectoral fins usually large and pointed• Five to seven gill slits

• Most sharks swim continuously to ventilate gills• Whale shark = Largest fish species (to 14+ m)

• Planktivorous (zooplanktivorous) – How?• Most prevalent in tropical coastal waters• Reproduction

• Internal fertilization (claspers)• Viviparous• Ovoviviparous• Oviparous

Swell shark

Horn shark

Egg Cases

Fig. 10-7 Claspers

I. Fishes – Overview

B. Chondrichthyes (Cartilaginous fishes)2. Rays and Skates

• Body dorsoventrally flattened• Often live on/near bottom (demersal)• Dorsal spiracles, gill slits (five pairs) on ventral surface• Pectoral fins flat and greatly expanded, often fused with head; no

anal fina. Stingrays

• Whip like tail with hollow spine (poisonous) at base• Eat small animals, including mollusks, crustaceans and fishes

b. Electric rays• Stun prey and defend against predators

c. Swimming rays (pectoral propulsion)• Eagle, manta rays

d. Skates• No whip-like tail• No stinging spines• Lay egg cases - mermaid’s purse (rays bear live young)

e. Sawfishes, guitarfishes• Euryhaline• Feed on benthic invertebrates• Electroreceptors in “saw”

SawfishGuitarfish

I. Fishes – Overview

B. Chondrichthyes (Cartilaginous fishes)3. Chimaeras

• Upper jaw attached to skull (unlike other cartilaginous fishes)

• Single pair of gill slits covered by operculum• Most common in deep water• Feed on benthic crustaceans, mollusks, fishes

• Bony plates; no teeth• No cloaca

Fig. 10-11

I. Fishes – Overview

C. Sarcopterygii (Lobefins)• Coelacanths (marine) and lungfishes

(freshwater)• Pelvic & pectoral fins w/thick muscle around

rod-shaped bone; similar to tetrapods• Primitive; coelacanths thought to be extinct until

early 20th century• Coelacanths

• Two extant spp.• Only in deep water• Ovoviviparous

Lungfish

I. Fishes – Overview

D. Actinopterygii/Osteichthyes (Bony fishes)• More than 26,000 species• Skeleton made of bone• Ganoid (thick, rigid), Cycloid (round, smooth) or ctenoid

(spiny) scales made of bone• Cycloid, ctenoid: thin, flexible, overlap

• Bony operculum covers gill chamber on each side• Caudal fin usually homocercal (vs. heterocercal in

sharks)• Fins composed of fin rays connected by thin membranes• Mouth typically terminal

• Jaws have more freedom of movement than in sharks

• Swim bladder to regulate buoyancy• Helps to compensate for dense bony skeleton

Fig. 10-14

Fig. 10-13

Fig. 10-15

II. Fishes - Biology

A. Body Shape• Strongly related to lifestyle1. Fusiform, streamlined

• Sustained high speed (up to 50+ mph)• Ex: Tunas, mackerels, marlins

2. Laterally compressed• Slow cruising, occasional burst swimming• Ex: Snappers, wrasses, butterflyfishes

3. Flattened• Sedentary, often demersal• Ex: Flatfishes (flounders, halibuts, soles), sea robins

4. Unusual, irregular• Often with camouflage color/pattern• Ex: Sargassum fishes, seahorses, trunkfishes, anglerfishes

5. Elongate, eel-like• Cryptic, living in tunnels, crevices• Ex: Moray eels, pipefishes, trumpetfishes

Fig. 10-16

II. Fishes - Biology

A. Body Shape• Strongly related to lifestyle1. Fusiform, streamlined

• Sustained high speed (up to 50+ mph)• Ex: Tunas, mackerels, marlins

2. Laterally compressed• Slow cruising, occasional burst swimming• Ex: Snappers, wrasses, butterflyfishes

3. Flattened• Sedentary, often demersal• Ex: Flatfishes (flounders, halibuts, soles), sea robins

4. Unusual, irregular• Often with camouflage color/pattern• Ex: Sargassum fishes, seahorses, trunkfishes, anglerfishes

5. Elongate, eel-like• Cryptic, living in tunnels, crevices• Ex: Moray eels, pipefishes, trumpetfishes

Fusiform

Video

II. Fishes - Biology

A. Body Shape• Strongly related to lifestyle1. Fusiform, streamlined

• Sustained high speed (up to 50+ mph)• Ex: Tunas, mackerels, marlins

2. Laterally compressed• Slow cruising, occasional burst swimming• Ex: Snappers, wrasses, butterflyfishes

3. Flattened• Sedentary, often demersal• Ex: Flatfishes (flounders, halibuts, soles), sea robins

4. Unusual, irregular• Often with camouflage color/pattern• Ex: Sargassum fishes, seahorses, trunkfishes, anglerfishes

5. Elongate, eel-like• Cryptic, living in tunnels, crevices• Ex: Moray eels, pipefishes, trumpetfishes

Laterally CompressedVideo

II. Fishes - Biology

A. Body Shape• Strongly related to lifestyle1. Fusiform, streamlined

• Sustained high speed (up to 50+ mph)• Ex: Tunas, mackerels, marlins

2. Laterally compressed• Slow cruising, occasional burst swimming• Ex: Snappers, wrasses, butterflyfishes

3. Flattened• Sedentary, often demersal• Ex: Flatfishes (flounders, halibuts, soles), sea robins

4. Unusual, irregular• Often with camouflage color/pattern• Ex: Sargassum fishes, seahorses, trunkfishes, anglerfishes

5. Elongate, eel-like• Cryptic, living in tunnels, crevices• Ex: Moray eels, pipefishes, trumpetfishes

FlattenedHalibut

II. Fishes - Biology

A. Body Shape• Strongly related to lifestyle1. Fusiform, streamlined

• Sustained high speed (up to 50+ mph)• Ex: Tunas, mackerels, marlins

2. Laterally compressed• Slow cruising, occasional burst swimming• Ex: Snappers, wrasses, butterflyfishes

3. Flattened• Sedentary, often demersal• Ex: Flatfishes (flounders, halibuts, soles), sea robins

4. Unusual, irregular• Often with camouflage color/pattern• Ex: Sargassum fishes, seahorses, trunkfishes, anglerfishes

5. Elongate, eel-like• Cryptic, living in tunnels, crevices• Ex: Moray eels, pipefishes, trumpetfishes

Irregular

Video

II. Fishes - Biology

A. Body Shape• Strongly related to lifestyle1. Fusiform, streamlined

• Sustained high speed (up to 50+ mph)• Ex: Tunas, mackerels, marlins

2. Laterally compressed• Slow cruising, occasional burst swimming• Ex: Snappers, wrasses, butterflyfishes

3. Flattened• Sedentary, often demersal• Ex: Flatfishes (flounders, halibuts, soles), sea robins

4. Unusual, irregular• Often with camouflage color/pattern• Ex: Sargassum fishes, seahorses, trunkfishes, anglerfishes

5. Elongate, eel-like• Cryptic, living in tunnels, crevices• Ex: Moray eels, pipefishes, trumpetfishes

Elongate

EelPipefish