Mr. Chapman
Biology 20
Norquay School
Fish Diversity Questions
Fish Diversity
Stephen Nowicki – Biology: Page 763 – 767
Using the Nowicki textbook, answer each of the questions that follow. It will be important to
know the answers to these questions not only for the exam next week, but also for the bony fish
(perch) dissection that will occur later in the week. Do not copy answers from the textbook –
attempt to put explanations into your own words.
1. What are gills?
Gills are large sheet of thin, frilly tissue filled with capillaries that take in
oxygen dissolved in water.
2. Briefly outline (point form is fine) how blood circulates inside of a fish.
Blood flows in a single loop throughout the fish, and travels through a heart
with two main chambers. The atrium collects blood and the ventricle
pumps it, allowing the blood to travel all the way around the fish,
collecting CO2 and leaving behind O2.
3. What is the name of the mechanism by which oxygen moves into a fish’s
blood and carbon dioxide moves out of it?
Diffusion is how oxygen moves into the blood and carbon dioxide moves
out of it.
4. What is countercurrent flow? How does it ensure that fish get the most
oxygen into their gills possible?
Countercurrent flow is the movement of water against the flow of blood in
the fish’s gills. It ensures that the concentration of oxygen in the blood is
always much lower than in the water, which allows oxygen to diffuse
easily.
5. Explain briefly the movement of a fish through water. What structures
allow the fish to remain stable against the flow of water?
Fish move in an S-shaped fashion; their muscles contract and produce Sshaped motions through the body, pushing them through water. Fins allow
Mr. Chapman
Biology 20
Norquay School
Fish Diversity Questions
the fish to remain stable, warding off changes in current and preventing
them from rolling in any one direction.
6. What is the function of teeth, and what did they evolve from? Why did
jaws give vertebrates a huge advantage as predators?
Teeth are used to capture and process food, and are thought to have
evolved from scales. Teeth gave vertebrates a huge advantage because
they turned them into strong hunters that could hold on to prey.
7. What is thought to be the original function of jaws?
Jaws were thought to originally be for retaining oxygen-rich water in the
mouth and preventing it from escaping the fish’s body.
8. Name the two groups of jawed fish that still exist today. How many were
there originally?
The cartilaginous fish and the bony fish exist today, but originally there
were 4 groups of fish.
9. How is the cartilage of cartilaginous fish unique? What is present in the
cartilage that provides this quality?
Cartilage of these fish is unique because it is stiffer and less squishy than
cartilage found in humans. Calcium deposits in the cartilage provide this
quality.
10. Cartilaginous fish are ancient, but have many advanced features. Make
a list of 4 features that make cartilaginous fish particularly successful, both
as hunters and in nature.
Internal fertilization, oil storage for movement through water, good
eyesight, excellent sense of smell, lateral line system.
11. What is a lateral line system? How does it explain why you can never grab
a fish in a tank easily with your hands?
Mr. Chapman
Biology 20
Norquay School
Fish Diversity Questions
A lateral line system is a system of canals on a fish that allow it to detect
even the slightest movements in water, allowing it to sense animals from a
distance.
12. Imagine that you were engaged in a fight-to-the-death underwater with
a shark. Somehow, you manage to poke his eyes out and plug his nose
completely, as well as destroy his lateral line system. You try to hide behind
a rock underwater, hoping the shark will lose you. Explain how the shark is
still going to find you and EAT YOU.
The shark has electroreceptive cells that allow it to detect and receive
electric signals. These signals can allow it to detect your heart beating
behind the rock, and that is what’s going to get you eaten.
13. Where can you find bony fish? What is the name of the protective plate
that covers the gill chamber?
Bony fish can be found practically everywhere, including tropical
freshwater streams and the Antarctic ocean.