#sipunculid

[shrimp-bird]

A Pacific peanut worm, Phascolosoma agassizii. This was my first time seeing an acorn worm and I was really puzzled. They're not uncommon animals and they are of decent size, about 8cm or 3 inches. Seeing an animal in a phylum I've never seen before is always exciting, and I was really taken in by the patterns. I originally assumed the visible parts were the whole animal, but it turns out they're concealing the more substantial portion of their bodies.

Photo source: https://sv.wikipedia.org/wiki/Phascolosoma_agassizii

(The video is mine and was edited for clarity)

[drhoz]

Behold..the Peanut worm, a worm like organism which is not actually a worm.It belongs to the group Sipunculida, which contains bilaterally unsegmented invertebrates. These are distributed worldwide from tropical inter tidal region to cold deep water.

They live in hard and soft substrate burrows and as well in old or empty gastropod shells, and are surface deposit feeders. Sipunculid is a poorly studied groups with only 5 scientific groups studying them. So all you aspiring young marine biologists why consider this cutie as your study of interest.

[drhoz]

#912 - Phascolosoma noduliferum - Peanut Worm

Another species that I failed to get a good photo of, but that are interesting enough that I don’t care.

Phascolosoma is a genus of small, thick, brown, rough Sipunculid worms, that really do resemble peanuts, but which can extend their head (and attendant mandibles and tentacles) out quite a distance when they’re hunting for prey. Phascolosoma noduliferum is a native of Australia’s southern coasts, where it lives under rocks or in shelly sand and gravel. I’ve found them in deep tide pools, where the surf can crash over the rocks. They’ll also live among ‘Sydney Coral’, and down to around 1500m.

Sipunculids don’t seem to have changed much since the Cambrian explosion - they’re not uncommon, even in shallow water, but most live in burrows or discarded shells, so aren’t seen. Some even bore into rock. The first species was described in 1827. A related species was later described as Golfingia macintoshii by E. Ray Lankester - who dissected the specimen between rounds at Saint Andrews golf club in Scotland.

[astronomy-to-zoology]

Sipunculus nudus

...is a species of sipunculid (peanut) worm native to subtidal zones and seabeds worldwide. Like most peanut worms S. nudus lives most of its life in a self-made sand burrow where it sits and feeds on any organic material that passes by its burrow. Like certain sea cucumbers S.nudus only exposes its fragile tentacles to feed at night, and mostly works on its burrow during the day. S. nudus is considered a delicacy and is commonly sold throughout southeast Asia. 

Phylogeny

Animalia-Sipuncula-Sipunculidea-Sipunculiformes-Sipunculidae-Sipunculus-nudus

Image Source(s)