Select the search type
  • Site
  • Web




Euphausia recurva

(Hansen, 1905)          

Shane Ovington (2014)



Fact Sheet



Physical Description


Life History & Behaviour

Anatomy & Physiology

Evolution & Systematics

Biogeographic Distribution

Conservation & Threats

References & Links

Physical Description


The euphausiacea is best characterised by its shrimp like appearance with a highly developed carapace fused with all thoracic segments. To differentiate the euphausiacea from the decapods (prawns, lobsters, crabs etc.) it can be noted that the carapace does not extend to the ventral side of the thoracic segments as it does in decapods. Another difference to be noted is the exposed gills present in euphausiacea unlike the brachial chamber present in other crustaceans.

Most of the euphausiacea display some form of bioluminescence to assist in schooling and mating displays. E.recurva did display this trait particularly under the microscope otherwise appeared a transparent yellow/brown colour with females often expressing darker colouration when holding eggs.  

E.recurva is a smaller member of the euphausiacea with most adults only reaching lengths of 10mm. Individuals reached sexual maturity at approximately 7mm as observed by individuals carrying eggs at this size.


Due to the large diversity of these shrimp like creatures between the true shrimp (decapods), mysid shrimp and krill (Euphausiacea) identification is often difficult. Due to size and limited studies on many of these taxa care must be taken in their identification. For the identification of this species two keys were used to improve accuracy and attempt to better understand the classification of these animals. The two classification keys used were Marine Species Identification Portal  and Intkey on crustacean identification. I focused more on the Marine Species Identification Portal due to a number of technical errors occurring in Intkey.

To first separate the krill from the decapods, the physical characteristics listed above were used. At this stage the key required the physical appearance of the eye, was it darkly pigmented or weakly pigmented followed by the shape, round or oddly shaped. Following these prompts with a darkly pigmented round eye the next distinguishing feature involves the shape of the frontal plate which is the most oral end of the carapace on the dorsal side. The frontal plate of this species is not truncated and its margins converged to form an acute angled pointed rostrum. The presence of spines behind the eyes (post ocular) was also a distinguishing characteristic that was absent in E.recurva.

At this point observations of the abdominal segments were made, to further divide the various taxa the presence or absence of mid dorsal spines was taken into account and the length ratios of the abdominal segments. E.recurva displayed no dorsal spines and a proportionally larger sixth abdominal segment to those surrounding it.


To identify the remaining species from one another it was required to compare the lappets. The Lappets are a small process extending dorsally from the first segment of the antennae.


In the case of this species the lappet was unforked and displayed a unique recurving leaflet only found of E.recurva. 

The marine species identification portal assisted in identifying this species through a thorough identification process. Although this process covered various features there is always the potential for error based on the perception of identifier and diagrams on the identification portal. There is a high diversity of shrimp like crustaceans in the worlds oceans and many that are yet to be discovered, despite their high ecological importance there is still many avenues to be explored in their identification.