Class Crustaceans
Answers are for parents and teachers.
1
List the crayfish’s limb types (maxillipeds, claws, walking legs, swimmerets) and their jobs.
Maxillipeds – push food and move water; claws – catch food; walking legs – crawl; swimmerets – carry eggs, and tail fan for swimming.
2
Compare the nervous systems of crayfish and earthworm.
Both have supra-/sub-pharyngeal ganglia, a nerve ring and a ventral nerve cord. The crayfish also has compound eyes and a balance organ.
3
How does the crayfish protect itself from enemies? Write 3 ways.
Protective colour, hiding under stones by day, backward escape with the tail fan, claws.
4
Write the importance of marine crustaceans.
Caught for food (crab, lobster, shrimp) and food for fishes and whales.
5
Why is the woodlouse useful for soil?
It digs burrows that loosen the soil and eats plant remains, enriching soil with humus.