Members of the phylum Ctenophora are known as sea-gooseberries or comb-jellies, and are startlingly beautiful marine invertebrates. They are commonly mistaken for jellyfish, but belong to their own group that is totaally unrelated to jellyfish (3). Pleurobrachia pileus has a transparent spherical body bearing two feathery tentacles, which can be completely drawn back into special pouches. The name comb-jelly refers to the eight rows of hair-like cilia present on the body, which are known as comb-rows. The rhythmic beating of these cilia enables the animal to swim, and also refracts light, creating a multi-coloured shimmer (2).
Despite their delicate, almost ghostly appearance, sea-gooseberries are voracious predators, feeding on fish eggs and larvae, molluscs, copepod crustaceans, and even other sea-gooseberries (5). Prey is caught by the long tentacles, which act as a net and bear adhesive cells known as colloblasts. The tentacles are then ‘reeled in’ and the prey is passed to the mouth (2).
This species is hermaphroditic. Breeding occurs from spring to autumn; the eggs and sperm are released into the water and fertilisation therefore occurs externally. The larva, known as a ‘cydippid larva’ is free-swimming. Most individuals die following spawning. This species may be preyed upon by fish and other sea-gooseberries (2).
Large and diverse group of minute marine and freshwater crustaceans belonging to the subclass Copepoda. They usually have an elongated body and a forked tail.
Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
Possessing both male and female sex organs.
Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
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