Round 1 - Phylum Priapulida
(Sources - 1, 2, 3, 4)
Priapulida is a phylum of unsegmented marine worms commonly known as “Penis Worms,” due to their general shape and retractable proboscis.
Like kinorhynchs (which seem to be their closest relatives) they live in the mud of shallow waters worldwide. Larger species tend to live in colder seas while smaller species live in warmer waters. They range from 0.2–0.3 cm to 39 cm (15.35 in) long. Their body is divided into a main trunk/abdomen and a swollen proboscis region, called the presoma, ornamented with ridges. The presoma, with the mouth at the tip, can be retracted into the trunk and is used in locomotion as well as in feeding. Members of the family Chaetostephanidae secrete a gelatinous tube, open in both ends, which they live in. Most families are carnivores that feed on slow moving invertebrates such as annelids, but some feed on detritus while others are filter-feeders. They have separate sexes, and usually breed by releasing sperm and eggs into the water, though at least one species is known for internal fertilization.
Priapulid-like fossils are known from the Middle Cambrian, with modern groups appearing in the Carboniferous. They were likely major predators of the Cambrian seas. The mouth of priapulids seems to be an original trait inherited from the last common ancestor of both priapulids and arthropods, though arthropods no longer possess it.
How do you feel about this phylum?
One or more of my favorite animals is in this phylum
I love one or more of these animals
I like one or more of these animals
I am neutral about all of these animals
I dislike all of these animals
I hate all of these animals
Propaganda under the cut
