Boldly coloured and patterned nudibranch: Halgerda sp. Photo: Arthur Anker
The colours and patterns of the sea slugs warn predators of their toxicity. This nudibranch is Chromodoris annulata. Photo: Arthur Anker
Segmentation, a distinguishing feature of the annelids, is clearly visible here. Photo: Alexander Semenov
Much of the body of a brush-head is shielded by chitinous plates. The head bears a mouth cone equipped with stylets and numerous scalds (Phiciloricus sp). Photo: Phil Miller
The individual hexagonal units making up the compound eye of a parasitoid wasp. Compound eyes made up of many discrete units are characteristic features of many arthropods (unidentified chalcid). Photo: Tomas Rak
The spherical test and impressive spines of a sea urchin (Coelopleurus floridanus). The mobile spines offer protection from predators. Since this species lives in relatively deep water, the purpose of the bright pigments in the skin and underlying skeleton is unknown. Photo: Arthur Anker
A jellyfish (Bougainvillia supercilious) with a hitchhiking amphipod (Hyperia galba). Photo: Alexander Semenov
The calcareous skeleton of a sea star allows for the formation of defensive structures such as spines. In this species (Acanthaster planck), the fragile spines break off easily, remaining in the skin of an attacker and releasing irritants. Photo: Alexander Semenov
In the cnidarians, what looks like a single individual is often a colony of polyps with specialized functions. In this floating colony (Porpita sp.) there are polyps for providing buoyancy, feeding (tentacles), digestion and reproduction. Photo: Arthur Anker
A stalked jellyfish (Lucernaria quadricornis). These cnidarians can be regarded as an overgrown polyp, one end of which has partly differentiated into a medusa. The ‘tufts’ of the feeding tentacles are clearly visible. Photo: Alexander Semenov