Overgrowing mat tunicate
Trididemnum solidum
(Van Name, 1902)
Description:
The zooids are embedded in a tough, leatherly tunic. Their excurrent siphons empty into thin internal chambers that have relatively small outflow openings. The incurrent siphons are small and scattered over the surface of the tunic. The tunic is in shades of gray, but can be blue green, green or white; it is rather hard through the abundance of stellate spicules.
Habitat:
Inhabit shallow reefs. Encrust and often overgrow living corals and sponges. Also in lagoons on mangroves.
Distribution:
Common Florida, Bahamas and Caribbean.
Remarks:
Positive identification requires microscopic examination of the internal body parts. The zooids have a branchial sac with three rows of stigmata, a single testis about which the sperm duct is spirally coiled and lack an atrial languet.