Shark Bio Exam

Name all the body parts XD

Snout, nostril, eye, spiracle, labial furrows, gill openings, pectoral fin, 1st and 2nd dorsal fins, pelvic fin, clasper (males), anal fin, keel, precaudal pit, encoche, caudal fin

What sets elasmobranchiomorphi apart from the rest of gnathostomata?

Placoid Scales

What kind of scales do chondrichthyes have?

Placoid scales!

Chondrichthyes vs Chondrostei?

Chondrichthyes: Cartilaginous fishes, placoid scales

Chondrostei: subclass of actinopterygii, ganoid scales

Chondrichthyes subclasses?

Elasmobranchi: Sharks, skates, and rays

Holocephali: Chimaeras, ratfishes

Why are the differences in shark teeth significant?

Shark teeth are a key meristic/morphological identifier for shark species

Oviparous reproduction

Egg laying, eggs are laid in an egg case

Ovovivparous reproduction

Eggs are formed inside the mother, and then hatched, the pups are born alive

Viviparous reproduction

Shark pups are born live after developing in the mother

What does parental investment do?

Parental investment influences the evolution of animal behavior

Holocephali characteristics

Distinguishing features, head claspers, and chimaeras are the only fish with true respiratory nostrils

Horn sharks

Heterodontiformes

Total of 8 species

Example: Port Jackson Shark

Carpet Sharks

Orectolobiformes

Have 5 gill slits, two spineless dorsal fins, an anal fin, no nicitating eyelids, a mouth in front of their eyes, and short snouts. Generally bottom dwellers

39 species

Example: Nurse Shark or Whale Shark

Ground sharks

Carcharhiniformes

Largest order of sharks with 227 species

Five gill slits, nictitating eyelids, and a long snout

Example: Hammerhead sharks

Mackeral sharks

Lamniformes

no nicitating eyelids, and a pointed snout

17 species in 7 families

Example: Megamouth, basking, thresher

Frilled and 6-7 gill sharks

Hexanchiformes

The most ancient order of sharks

6 or 7 gill pairs, single posterior dorsal fin

6 total species

Example: Bluntnose 6-gill

Dogfish sharks

Squaliformes

5 gill slits, no anal fin, no nictitating membrane, short snout

Generally, the smallest order of sharks

126 species

Example: Greenland shark, Spiny dogfish

What are Batoids?

The division of cartilaginous fishes that includes skates and rays

Benthic or pelagic; pectoral fins enlarged, fused with head; gill slits ventral; spiracle large; pavement teeth

Angel sharks

Squatiniformes

no anal fins, no nictitating eyelid, mouth at the front of the head, and a short snout

12 species

Saw sharks

Pristiophoriformes

a long snout with barbels and gills on the sides

Saw fish

Pristiformes

Gills on underside, no barbels

Differences between skates and rays?

Rays: pelvic fin with one lobe, is ovoviviparous, no fins on tail

Skates: pelvic fins with two lobes, lay eggs (oviparous), dorsal fins on tail

Stingrays

Myliobatiformes

1 smaller dorsal over pelvic fin, depressed body, whip-like tail, enlarged pectorals, ovoviviparous supplemented with uterine milk

Example: Spotted eagle ray

Skates

Rajiformes

Slender tail, no sting, tail has two small dorsal fins and a tiny caudal fin, oviparous

Example: clearnose skate

Guitarfishes

Rhinobatidae

Preoral snout or broadly rounded, thick shark-like trunk or flattened and covered with denticles, ovoviviparous

Example: Sharkfin guitarfish

Electric rays

Torpediniformes

thick, depressed body without denticles, no sting, paired with pectoral electric organs in disk, ovoviviparous