Undersides of Rocks


Scale worms - segmented worms (annelids) up to about 6 cm in length, but usually much shorter and very flat. They may roll into a ball if disturbed.

Anemones - short, tubular, jelly-like bodies that may be 6-10 cm in length but usually much shorter (1-2 cm). Note the short tentacle surrounding the mouth. The tentacles have stinging cells to stun their prey (crustaceans and small fish), after which the tentacles pass the food into the mouth. When disturbed, anemones pull in their tentacles, contract and adhere tightly to the substrate.

Flat worms - non-segmented worms 1-3 cm in length. Surface of their body ripples as it moves over the surface of the rock. Very flat, thin body.

Sponges - large, irregular encrustations on rocks. May be yellow, orange, brown, red or green in colour. The body of the sponge contains numerous incurrent pores which lead internally to a central cavity lined with cells with flagella. The movement of the flagella draws water in through the incurrent pores and out through excurrent pores or oscula. The oscula a larger and fewer in number than the incurrent pores. The oscula should be visible on the surface of the sponge. Cells lining the body cavity remove food particles and oxygen from the water stream and release carbon dioxide and wastes.

Other species: limpets, dog whelks, periwinkles, dog whelk egg capsules.