Checklist of Tanzanian Cnidaria

Cnidaria is a phylum containing over 9,000 species found exclusively in aquatic and mostly marine environments. It is a large phylum composed of some of the most beautiful of all the salt and freshwater organisms: the true jellyfish, box jellyfish, corals and sea anemones, and hydra. Cnidarians are classified into four main groups: the almost wholly sessile Anthozoa (sea anemones, corals, sea pens); swimming Scyphozoa (jellyfish); Cubozoa (box jellies); and Hydrozoa, a diverse group that includes all the freshwater cnidarians as well as many marine forms. Anthozoa (true coral, sea anemones, sea pens) has about 6000 species, Cubozoa (box jellyfish) about 20 species, Hydrozoa (freshwater hydra, fire coral) about 3000 species and Scyphozoa (true jellyfish) about 200 species worldwide (http://www.angelfire.com/mo2/animals1/phylum/jellyfish.html). All the main groups (classes) Cnidaria (Anthozoa, Scyphozoa, Cubozoa and Hydrozoa are found in Tanzania (Table 1). Only the marine species were considered during the preparation of the Cnidaria checklist. Fresh water Cnidarians will be considered at a later stage in the near future. Marine Hydrozoans, Cubozoans and Scyphozoans are very much under-represented mostly because most marine research (taxonomists) has concentrated on the charismatic Anthozoans, especially calcareous coral reef organisms, which are relatively stable (easy to handle taxonomically). We believe further literature reviews and research will reveal additional records. Thus, the Cnidaria species checklist presented should be regarded as a preliminary contribution. The present checklist contains 365 verified Cnidarians in Tanzania out of about 9000 known globally. The Order Scleractinia (hard corals) contains more than half (236 species) of the verified Cnidarians (Table 1). The Order Alcyonacea (soft corals) is the second numerous group with 80 verified species followed by Actiniaria (sea anemones). Other Orders of Anthozoa such as Corallimorpharia and Zoanthidea were represented by 5 and 4 species, espectively, while Ceriantharia, Helioporacea, and Pennatulacea were represented by single species each. In the checklist, there are 15 Orders of Cnidaria divided into 62 families, and 142 genera. Source of information for the Cnidaria checklist comes from the following publications: Hamilton and Brakel (1984), Sheppard (1987), Johnstone et al. (1998), Veron (2000), Richmond (2002), Schleyer et al. (2003), Obura et al (2004) and personal observation of checklist compilers. Species were crosschecked with those listed in the World registration of Marine Species (WoRMS).