biology 7.4 - ventillation in fish and insects

Why do fish need to be so adapted to get enough oxygen?

There is a lower concentration of oxygen in water than in the air

How are fish adapted to get enough oxygen?

• water enters the mouth and leaves through the gills

• Each gill made of thin branches called gill filaments / primary lamellae = big surface area

• The primary lamellae are covered in gill plates / secondary lamellae = increases surface area

• Each gill plate is supported by a gill arch

• Gill plates have lots of capillaries and a thin surface layer

What is the counter current system?

The blood in the capillaries and the water outside the fish move in opposite directions = the concentration of oxygen is always greater in the water than in the blood

What are the steps for the gills in bony fish to be ventilated?

1. Fish opens mouth = buccal cavity’s floor lowers = volume is increased and pressure decreases = water sucked in

2. Fish closes mouth = buccal cavity’s floor rises = volume decreases = pressure increases = water forced out of buccal cavity and across the gill filaments

3. Each gill is coved by the operculum (bony flap that protects the gills) which opens due to the increased pressure so water can leave the gills

What do you do when dissecting a fish?

Wear a lab coat and gloves and cut gill arch through the bone to remove the gills

What are the microscopic air filled pipes in insects called?

Tracheae

What are spiricles?

Where air moves through in insects surface

What are tracheoles?

They are branches off of the tracheae with thin permeable walls and go inside of individual cells. They contain fluid that oxygen dissolves in

How do insects change the volume of their bodies and move air in and out of the spiracles?

Rhythmic abdominal movements

How else do large insects pump their thoraxes (as will as abdominal movements)?

Wing movements

What supports the tracheae?

Rings of chitin

How do you dissect insects?

Remove part of the exoskeleton form along the length of the abdomen, then use a syringe to fill the abdomen with saline solution to see silvery - grey tracheae (as filled with air)