Lecture 9

Question 1

Respiration in cartilaginous fish

Answer 1

Water enters through the gill chambers through the mouth or the spiracles and exits through the gill slits
The spiracles provide oxygenated blood directly to the eye and brain
Blood in the gill filaments absorbs oxygen from the water

Question 2

Explain how circulation works in a shark

Answer 2

A sharks heart is a two chambered S-shaped tube, small in proportion to body size.
Blood flows from the heart to the gills and then to body tissues.
Many sharks have to swim continuously to circulate blood throughout their bodies.

Question 3

What are Acanthodii?

Answer 3

Spiny sharks

They had subterminal mouths

Spines associated with all fins except the caudal fin

Onion like scales

Heterocercal tail

Question 4

How does a sharks sense of smell work?

Answer 4

Sharks determine the direction of a sent based on the timing of scent detection in each nostril