Vetericaris chaceorum

Anchialine Pool Shrimp

FWS Focus


Vetericaris chaceorum is a small shrimp found in anchialine pools on the island of Hawaii, is a member of the family Procarididae, and is considered one of the most primitive shrimp species in the world (Kensley and Williams 1986, pp. 428–429). Vetericaris chaceorum is approximately 1.77 to 2 inches (in; 45 to 50.8 millimeters (mm)) in total body length excluding the primary antennae, which are approximately the same length as the adult’s body length (Kensley and Williams 1986, p. 419) and is the largest of the anchialine pool shrimp found in Hawaii (Yamamoto et al. 2015, p. 40). This species tends to be a yellowish-orange color from its carapace to the sixth abdominal segment with translucent appendages (Fransen et al. 2013, p. 630). The species lacks large chelapeds (claws) (Kensley and Williams 1986, p. 426), which are a key diagnostic characteristic of all other known shrimp species. V. chaceorum is largely devoid of pigment and lacks eyes, although eyestalks are present (Kensley and Williams 1986, p. 419). Observations of Vetericaris chaceorum indicate the species is a strong swimmer and propels its body forward in an upright manner with its appendages held in a basket formation below the body. Forward movement is produced by a rhythmic movement of the thoracic and abdominal appendages, and during capture of some specimens, V. chaceorum escape tactics included only forward movement and a notable lack of tail flicking, which would allow backward movement and which is common to other shrimp species (Kensley and Williams 1986, p. 426). No response was observed when the species was exposed to light (Kensley and Williams 1986, p. 418). This species is characterized as hypogeal, which means that these shrimp occur not just in the illuminated parts of the anchialine pool but also in the interconnected water table below (Brock and Kam 1997, pp. 5-6). These hypogeal parts or interstices of the anchialine pools are where shrimp like V. chaceorum are able to move between pools (The Nature Conservancy 1987). This species is most commonly found midwater in the water column and is characterized as a strong swimmer with propulsion provided by both its primary thoracic appendages (pereiopodal exopods), as well as its abdominal appendages (pleopods) (Kensley and Williams 1986, p. 426). Visual acuity of V. chaceorum is unknown, but individuals showed no observable responses to light being shone on the animals (Kensley and Williams 1986, p. 426). Lau (2012, in litt) noted that little if any pigmentation was seen in the area of the eyestalks, but shrimps navigated over rocks and substrate without a problem, which indicates the presence of other sensory features. Based on their presence in parts of anchialine pools with extremely low oxygen tension, V. chaceorum appears to tolerate low oxygen levels (Lau 2012, in litt).

Scientific Name

Vetericaris chaceorum
Common Name
Anchialine pool shrimp
FWS Category

Location in Taxonomic Tree

Identification Numbers



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