Rachel Lynette, River food chains, Londres, Raintree, 2011, p. 17.
Cassis Fly Larvae
A caddis fly larva has an unusual adaptation that helps it build a hard, protective case. It uses a glue-like substance from its own body along with sand, shell pieces, leaves, and twigs to build its case. It takes the case wherever it goes. When it outgrows a case, it must build another. The caddis fly larva seals itself in the last case it builds. Then it changes into its winged adult form.