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Barrel sponge
(Xestospongia testudinaria)
[Photo: E. Hickerson, Flower Garden Banks National Marine Sanctuary] |
Porifera, or sponges, are the dominant sessile (attached) invertebrates in the Gulf of Mexico. There are over 5000 species of sponges worldwide, with 339 species documented in the Gulf. Sponges are found in all marine environments from shallow, intertidal pools to the deep ocean. Poriferans are benthic, residing on solid substrata such as reefs, mangrove stilt roots, seaweed, and deep-sea rock outcrops.
Poriferans are filter feeders, pumping large quantities of water through their bodies by means of beating flagella. The water moves unidirectionally through a system of canals, bringing in food and oxygen, and transporting out waste. Sponges range in size from 1 mm to 1 meter and come in a variety of shapes (sheet-like, tubes, mounds, etc.) and colors.
Sponges are hermaphroditic, and reproduce both sexually and asexually. After fertilization, sponges produce planktonic larvae that settle to the sea floor and develop into juvenile sponges. Poriferans reproduce asexually via budding and gemmules. Gemmules are small buds that are encapsulated in a protective covering that safeguard the cells during hostile conditions and will resume growth when conditions become favorable.
(Information from
Gulf of Mexico, Origins, Waters and Biota: Volume 1, Biodiversity,
Texas A&M University Press, 2009).
Other Resources:
UC Berkeley, Museum of Paleontology, Porifera