|Cape acorn worm
The Acorn worms or Enteropneusta are a hemichordate class of invertebrates, closely related to the chordates. There are about 70 species of acorn worm in the world, the main species for research being Saccoglossus kowaleski.
All species are infaunal benthos that either may be deposit feeders or suspension feeders. Some of these worms may grow to be very long; one particular species may reach a length of 2.5 meters , although most acorn worms are much, much smaller.
Most acorn worms range from 9 to 45 centimetres in length, with the largest species, Balanoglossus gigas, reaching 1.5 metres or more. The body is made up of three main parts: an acorn-shaped proboscis, a short fleshy collar that lies behind it, and a long, worm-like trunk. The creature's mouth is located at the collar behind the proboscis.
The skin is covered with cilia as well as glands that secrete mucus. Some produce a bromide compound that gives them a medicinal smell and might protect them from bacteria and predators. Acorn worms move only sluggishly, using ciliary action and peristalsis of the proboscis
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