Invertebrates

Copepods can be divided into 3 main feeding groups, herbivores, mixed feeders and carnivores (Wickstead 1962). Herbivorous copepods filter feed on phytoplankton contained in the falling detritus marine snow. Larger copepods tend to be more often carnivorous and eat other zooplankton; however locating prey at this depth is a challenge. Due to the lack of light, organisms require the use of other senses to detect and locate prey, of which the most important are chemoreceptors and mechanoreceptors (Fuzessery and Childress 1975). Some copepod species have been found to have chemoreceptors around their mouth parts (Buskey 1984) which enable them to discern the difference between food and non-food particles when filter feeding (Buskey 1984). It is thought that the more carnivorous species of copepods use mechanoreceptors on their antennae to detect movement in the surrounding water by prey (Buskey 1984). However, it may often be a combination of these two senses that is used to detect prey.

Figure 9. Marrus orthocanna, a deep sea siphonophore (Siphonophores)

Siphonophores (Figure 9) are a one of the more important predators of the bathypelagic zone. These colonies are composed of many individuals, with each serving a specific function. They have tentacles made up of dactylozooids which contain stinging nematocyst cells which they have for protection and use to catch their prey (Dunn 1982). These cells paralyse the prey and its gut has adapted to rapidly digest food (Hartman and Emery 1956). It is believed that some species feed on bathypelagic organisms which live around the sea floor (Hartman and Emery 1956).

Figure 10. Vampyroteuthis infernalis, the vampire squid can fold its arms back over its body. No explanation has so far been found for this behaviour (Nopokemeo)

A very unique organism known as the Vampire squid, Vampyroteuthis infernalis (Figure 10), is in fact both part squid and part octopus and is the only species in its order, Vampyromorphida, that is still alive today. It has eight arms like an octopus but also has two other arms inside the dome made by the other eight, not unlike the tentacles possess by squid (Siebel et al. 1998). Among its known prey are copepods, prawns and cnidarians but little else is known about how it captures its prey (Young 1977). It does possess photophores at the tips of its arms which it can flash, which are thought to be mainly used to deter predators but may also be used to attract prey.

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