We all know about earthworms, those immensely useful garden animals that turn vegetable scraps into enriching worm poo. Many of their distant cousins in the sea lead quite different lives and some are quite active hunters. Polychaete worms are called this because they have many (poly) bristles (chaetae). Like earthworms they have soft, cylindrical bodies divided into segments but each segment has clusters of bristles and/or paddle shaped attachments. The paddles are often filled with blood vessels which allow the animals to take in oxygen from the water and release carbon-dioxide.

The most familiar of the free-living predatory polychaetes are probably the beach worms. Skilful fishers catch them for bait – luring them with a piece of smelly meat or fish then grabbing the exposed head with pliers or fingers. There are at least six species from Queensland to South Australia, some growing to 3m long.

Beach worms have a distinct head with eyes and sensory tentacles at the top and a mouth below. The throat, or pharynx, can be pushed out and has horny jaws which grab hold of the prey. The first few segments of the worm are stronger and wider than the rest and have stout bristles and bigger paddles for digging and holding on to the sand. As any fisher will tell you, it’s much easier to extract the worm if you can get hold of those first segments and pull them free of the sand. The hundreds of remaining segments bear comb-like gills that are for breathing.

Pipis are one of the animals on which beach worms prey but they also eat decaying meat, fish and seaweeds.

On some of the Nature Coast Marine Group’s rock rambles we have come across another spectacular polychaete predator, the Irridescent Worm (Eunice sp.) This worm can be over 35 cm long and as thick as a finger when contracted. It is dark purple-brown or brown-red often with purple iridescence while the fourth body segment has a white bar. Five ringed antennae are at the front of the head and an additional pair of tentacles are on the segment behind.

This worm lives under stones at low tide where it moves quickly with the aid of its paddles and muscular snake-like body. It scavenges and hunts small crustaceans and worms. Like beach worms, its powerful jaws can bite humans.