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Euphausia recurva

(Hansen, 1905)          

Shane Ovington (2014)



Fact Sheet



Physical Description


Life History & Behaviour

Anatomy & Physiology

Evolution & Systematics

Biogeographic Distribution

Conservation & Threats

References & Links

Life History & Behaviour


Krill vary highly in their main feeding style with most feeding on zooplankton, some phytoplankton, detritus and other more predatory. E.recurva used its filamentous endopods to filter through sediment and also filter feed in open waters for zooplankton. Once food is caught on the endopods it is retracted towards the mouth whereby the maxillae move it to the mandibles and into the mouth (Ruppert, et al. 2004).   


The breeding cycle of recurva has not been comprehensively studied but the larval stages are well known and consistent throughout the majority of Euphausiids. The genus Euphausia generally eggs are shed freely with some species (recurva included) brooding them for some time to improve reproduction success (Brinton, 1973). Observations of this process were made for recurva, multiple stage of development of the eggs was made but it was found they were all expelled at a similar stage. Euphausiaceans generally expel their eggs into the water column near the surface and only reproduce when there are high nutrients available. Generally higher temperatures are better conditions for spawning, warmer waters means faster development and hence lowered chances of predation (Dalpadado, 2006).



The euphausiaceans undergo a multiple staged life cycle. The way in which this is carried out varies with the ecology of each species but the stages remain much the same. Once fertilisation has occurred the eggs are released into the water column or stuck to sediment (species dependent) and begin to undergo development (Dalpadado, 2006). The egg then hatches in to the first larval form known as the nauplius, this larval form is used in the beginning of the ascent to the surface and progressively undergoes development but is not yet capable of feeding (Ikeda, 1984). The nauplius then progresses to a metanauplius which is slightly more mobile and is beginning to develop feeding structures. Each of these stages requires a molt to progress to the next larval stage (Maas & Waloszek, 2001). The metanauplius progresses to the calyptopis which is the first stage capable of feeding and shows some form similar to that of the Euphausia body plan. The final larval stage, the furcilia is completed near the surface which then underdoes a final molt to establish the juvenile form of the species (Ikeda, 1984).

Picture (Life cycle)

Respiration & Movement

The euphausiacea have external gills located at the base of the exopods. These exopods move rhythmically to assist in ventilation of the gills. Their biramous legs (split in to at the tip) also assist in bring fresh water in and over the gills. To swim krill use their large pleopods (appendages extending ventrally form abdominal segments) by synchronising their movements to propel themselves through the water column (Ruppert, et al. 2004).

Watch this video for a good visual representation of these movements (Movement)