Polychaetes are segmented, marine worms of the phylum Annelida, and are thus related to other annelids such as earthworms and leeches. Polycheates, comprising some 10,000 species, have planktonic larvae and most are benthic as adults. Tomopteris spp. are holoplanktonic, living in the plankton their whole life. Larvae of Polygordius spp. are very abundant in the Mid-Atlantic plankton.

Polygordious jouineae

(exolarvae)

Polygordious sp.

(endolarvae)

Tomopteris sp.

(holoplanktonic)

Various species

(Presettlement larvae)