Introduction: The ecological niche of the shrimp Palaemon Affinis .
The Palaemon has the following taxonomic position.
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Phylum Athropoda.
Class Crustacea.
Subclass Malacostraca.
Order Decapoda.
Suborder Pleocyemata.
Infraorder Carida.
Family Palaemonidae.
Genus Palaemon.
The Palaemon Affinis (Affinis) is a very common almost transparent shrimp that is found all over New Zealand. The transparency is a brilliant approach that is, in view the ultimate camouflage. Instead of colouring itself like its environment it is see-through. From personal experience they are very hard to spot when stationary. According to Kirkpatrick a small Affinis is 7-12mm a medium is 13-17mm while a large Affinis is 18-26mm. The Affinis is able to swim back and forth with its abdominal limbs and in quick bursts backwards with strokes of its curved tail. The quick swing of its tail is an ability that allows it to quickly retreat into a less exposed crevice. When not threatened it attempts a half walk half swim I would call a swalk thus allowing the over exertion and increased energy use of swimming to be lessened. Due to the vulnerability of the shrimp it is found in the crevices of rock pools where it is safe from many of its predators. The prawn uses gills for breathing which allow it to survive underwater and has an exoskeleton but would still dry out if left on dry land. The Affinis feeds on decaying plants, young barnacles, amphipods and even young shrimp. Specialising in feeding on decaying matter is an asset to the shrimp as decaying plants like algae can lower oxygen levels to dangerous levels in the rock pool. When feeding it grabs food with its slender Chelae before retreating to a safe shelter. This behavioural adaptation allows it to keep safe from predators and not be caught out in the open while feeding. .
Found in the majority of rock pools are many types of algae, hydroids, polyzoans, gastropods and crustaceans.
