Cartilaginous Fish Test Study Guide

What is the number of cartilaginous fish species alive today?

Close to 1000

What is the number of shark species today?

Close to 500

When did cartilaginous fish first appear in the fossil record?

400 million years ago

What are the top four most dangerous sharks?

Great White, Tiger, Bull, Oceanic White Tip

What are two reasons why most sharks have to swim continuously?

They cannot breathe/have brain function when water is not running over their gills, and they do not have swim bladders so they cannot stay afloat in the water if they don’t keep swimming.

How is shark tail size/shape a good indicator of speed?

Symmetrical tails and longer upper tail fins are found on fast moving sharks

How is shark dorsal fin size a good indicator of speed?

Sharks with larger dorsal fins are faster

Why are shark teeth replaced?

Because they easily break off

How are shark teeth replaced?

When one breaks off or wears out, another rotates forward from the inside of the jaw to replace it

Describe shark skin and scales.

It looks and feels like it’s covered with tiny teeth, which are dermal denticles

What type of fertilization do sharks use?

Internal, meaning the eggs are fertilized inside the female’s body

What are the three methods of shark embryonic development?

Oviparous, ovoviviparous, and viviparous

How do oviparous pups get nourished?

Yolk

How do viviparous pups get nourished?

Placenta

How do ovoviviparous pups get nourished?

Yolk

What is the range of shark gestation periods?

9 to 22 months

Where are sharks’ touch receptors located?

Skin, barbels if applicable

Where are sharks’ taste recepters located?

Mouth, tongue, pharynx, barbels if applicable

Where are sharks’ smell receptors located?

Nose

Where are sharks’ hearing receptors located?

Tiny duct that carries sound waves where ears would be on either side, and can detect sound with lateral line system

Where are sharks’ electroreceptors located?

Snouts and lower jaws

Where are sharks’ vibration receptors located?

Snout, ampullae of Lorenzini

What’s significant about 40 Hz?

The frequency that is best detected by sharks’ electroreceptors

What is the composition of a shark skeleton?

Cartilage

How do sharks maintain buoyancy?

Large, oily livers and fin position which provides lift when they swim, like airplane wings

What is the role of the spiral valve, and how does its structure provide an adaptive advantage?

Increases surface area for absorption of food, increases absorption efficiency through their short, compact intestines

How do you identify a shark’s gender?

Females have cloacas and males have claspers, females are usually larger and rounder,

What is the role of the spiracle?

Intakes water into the buccal space before being expelled from gills

Why is it hard for sharks to sustain their own population?

They have a long gestation period and few pups per shark are born, they have low reproductive potential

What are physical differences between rays and skates?

Rays have long, whiplike tails, skates have thick, fleshy tails, rays have two venomous barbs while skates have sharp spikes or thorns, rays are usually bigger, rays have serrated plates for crushing while skates have small, pointy teeth

How do rays and skates develop their young?

Rays give birth to live pups while skates lay egg cases

What are the four characteristics of all Chordates?

Notochord, dorsal nerve cord, gills, tails

Which characteristic of Chordates develops into a vertebral column?

Notochord

What is the problem with shark conservation?

Shark fin soup is very popular and people are afraid of sharks so they justify killing them

Anal Fin

Back Dorsal Fin

Dorsal Fin

Eye

Gill Slits

Pectoral Fin

Pelvic Fin

Caudal Fin

Teeth