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Zoanthids
or Colonial
anemones
Order Zoanthidea
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Called
zoanthids, colonial anemones are common in the coral rubble area.
They appear as groups of tiny, flower-like animals growing in the
sand or on coral rubble. They have short tentacles, and often a colourful
centre, where the tiny mouth is. When exposed at low tide, however,
they may retract their tentacles and look like strange tubular blobs.
Living together: Zoanthids belong
to the same group as sea anemones. While sea anemones are large solitary
polyps, many zoanthids are tiny polyps that are linked one another
in a colony. In some, each individual polyp has a rather long body
column. In others, they are short. The body columns may be joined
together by stolons (tube-like structures) or embedded in a common,
shared mat of tissue. The colony may form mats on the sand or encrust
rocky areas. Some zoanthids, however, may be solitary.
Toxic flowers: Some zoanthids
contain powerful toxins to protect themselves against predators. However,
some animals have adapted to the poison including the Common
hairy crab and nudibranchs. Some predators
even use the zoanthids' toxins to protect themselves.
Zoanthid food: Most of zoanthids
feed on plankton, some also feed on finer particles. Many harbour
zooxanthellae (symbiotic algae) inside their bodies. These carry out
photosynthesis and may contribute nutrients to the host polyp.
Zoanthid Babies: Zoanthids generally
reproduce asexually: new polyps bud off to enlarge the colony. However,
they also reproduce sexually. The polyps may produce sperm or eggs,
but usually only either one at a time. Eggs and sperm are released
simultaneously for external fertilization.
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quick
facts
Each polyp about 1-2cm in diameter, common in the coral rubble
area
Classification:
Subclass Hexacorallia
Class Anthozoa
Phylum Cnidaria |
