Heptacarpus sitchensis

Heptacarpus sitchensis (Brandt, 1851) Common name(s): Sitka coastal shrimp, Sitka shrimp, Red-banded transparent shrimp, Common coastal shrimp
Synonyms: Spirontocaris sitchensis, Hippolyte sitchensis, Heptacarpus pictus, H. littoralis
Phylum Arthropoda Subphylum Crustacea Class Malacostraca Subclass Eumalacostraca Order Decapoda Suborder Pleocyemata Infraorder Caridea Family Hippolytidae
	Heptacarpus sitchensis, two individuals about 2 cm long. Collected intertidally from the N Oregon coast.
	(Photo by: Dave Cowles, April 2014)


Description: Shrimp of Family Hippolytidae have no exopodites on their pereiopods. Pereiopod 1 is chelate rather than subchelate (photo), and the carpus of pereiopod 2 is subdivided into 3-7 multiarticulated units. A rostrum is present and often has spines but the spines are not movable. The eyes project out from under the carapace and are visible from above. Genus Heptacarpus has a toothed rostrum (photo) and 7 articles in its multiarticulated 2nd carpus (photo). Heptacarpus sitchensis has a well-developed rostrum slightly shorter than the postorbital carapace (photo), but not quite long enough to reach the end of the 2nd antennal scale. The anterior margin of the first segment (base of the peduncle) of the first antenna (antennule) has only one spine where it articulates with the second segment (photo). The species has no supraorbital spine (photo). The dactyls at the ends of pereiopods 3-5 have bifid tips (photo). The rostrum is well-developed and with spines, and reaches beyond the second article of antenna 1 (photo). It has a pterygostomial spine at the anteroventral margin of the carapace (photo). The pleuron of abdominal segment 4 has a ventral spine (photo). Pereiopods 1 and 2 and the 3rd maxilliped may or may not have an epipodite (photo). Note that this description is at variance with the description in the key but agrees with Wicksten et al. (1996) below. The 3rd maxilliped is just long enough to reach slightly past the end of the 2nd antennal scale (photo). Color variable, and is mostly lost at night. The carapace is often translucent, greenish, with distinctive thin oblique reddish stripes but the background color may be brown or even white. The legs have red bars. The abdomen is mostly clear or often bright green (photo). One reference states that both the carapace and the abdomen may have blue spots. Total length for females to about 34 mm, males smaller.

How to Distinguish from Similar Species:H. moseri has a much longer 3rd maxilliped which reaches beyond the antennal scale by at least half the length of its distal article, and it typically lives much deeper. H. stimpsoni has a shorter rostrum which reaches beyond the first segment of the peduncle on the 1st antenna but not as far as the middle of the 2nd antennal scale. H. paludicola's rostrum reaches past the end of the 2nd antennal scale.


Geographical Range: Resurrection Bay, Alaska to Baja California


Depth Range: Mid-intertidal to 12 m


Habitat: Can be abundant in mid- and low intertidal of rocky coasts and sublittoral, in Zostera eelgrass beds, and on floats.


Biology/Natural History: This is one of the most common intertidal shrimps along the US Pacific coast. The variable colors in this shrimp are mainly due to colors in the tissues rather than in the exoskeleton. The intensity of the color fades when the shrimp has not eaten much recently. Females mate and brood eggs more than once, molting between broods. Mating takes place rapidly, shortly after the female molts. The species may be parasitized by bopyrid isopods, especially in the Salish Sea area, which superficially appear to be a clutch of eggs carried under the abdomen. In Alaska this isopod species is Hemiarthrus abdominalis. Jensen (2014) says that H. paludicola may be a synonym of this species.

References:


Dichotomous Keys: Carlton, 2007 Kozloff, 1987, 1996


General References: Jensen (1995) Jensen (2014) Lamb and Hanby (2005) Morris et al., 1980 (as H. pictus) O'Clair and O'Clair (1998) Ricketts et al. (1985)


Scientific Articles: Bauer, R.T., 1976. Mating behavior and spermatophore transfer in the shrimp Heptacarpus pictus (Stimpson) (Decapoda: Caridea: Hippolytidae). Journal of Natural History 10: pp 415-440 Bauer, R.T., 1981. Color patterns of the shrimps Heptacarpus pictus and H. paludicola (Caridea: Hippolytidae). Marine Biology 64: pp 141-152 Wicksten, Mary K., Robyn Flynn, and Michael Fagarason, 1996. Heptacarpus pictus (Stimpson) synonymized with Heptacarpus sitchensis (Brandt) (Decapoda, Hippolytidae). Crustaceana 69:1 pp 71-75. DOI 10.1163/156854096X00097


Web sites:


General Notes and Observations: Locations, abundances, unusual behaviors: Heptacarpus sitchensis has a well-developed, toothed rostrum. None of the teeth are hinged (movable). This species' tissue is normally nearly clear. As with many shrimp, the whitish tinge appearing in the tissue here only appears when the animal is metabolically compromised and dead or nearing death. Live shrimp run so fast and so constantly that it is almost impossible to get clear photos of small body parts. Being decapods, shrimp such as Heptacarpus sitchensis have 5 pairs of pereiopods (walking legs). The 5 pairs can be easily counted in this photo. Anterior to the walking legs are 3 pairs of maxillipeds, which are legs specially modified for feeding. In this species the 3rd pair of maxillipeds is large; as long as the legs and more robust. The first pereiopod has a yellow-tipped chela. The second pereiopod is more slender and has a multiarticulated carpus. Pereiopods 3-5 are similar to one another but in this species their dactyl (tip) is bifid. As with many shrimp, the 2nd pereiopod is thinner and slightly longer than the other walking legs. The carpus of the 2nd pereiopod, here draped across the dissecting pin, has a series of constrictions that divide it into seven articles. This type of structure is called a multiarticulated carpus. Although Kozloff's key lists epipods at the bases of several pereiopods and the 3rd maxilliped, Wicksten et al., state that this trait is quite variable. Other references state that the epipods are often very small and hard to see. This view centers on the 2nd pereiopod (thin leg near middle). The 1st pereiopod and 3rd maxilliped are to the right of it and the 3rd and 4th pereiopods are to the left. None of the leg bases has an obvious epipod. This view of the propodus and dactyl on pereiopod 4 clearly shows the bifid tip of the dactyl. This dorsolateral view of the carapace shows that the species has no supraorbital spine, which would be just above the eye near the base of the rostrum. It also shows that the rostrum is slightly shorter than the postorbital carapace. The orbit is the slot in the carapace to accommodate the eyestalk and is the official 'front' of the carapace (not including the rostrum). The postorbital carapace is measured from that slot at the base of the eye straight back to the posterior margin. Heptacarpus sitchensis has a pterygostomial spine at the anteroventral margin of the carapace, seen here just below the base of the 2nd antenna. The ventral margin of abdominal pleuron 4 (middle-right) of this species has a spine. Abdominal pleuron 5 (middle-left) has a similar spine. The third abdominal segment (top right) of hippolytid shrimp is usually bent, leading to the family name of "broken-back shrimp". This dorsal view of the head shows that the anterior end of the basal segment of the first antenna (antennule) has only one prominent spine near where it articulates with the second segment. This dorsal view of a live individual shows the normally transparent or translucent tissue, the pigmented oblique lines seen on the carapace and abdomen, and illustrates how the colors can change (compare this view to those above).

Authors and Editors of Page:
Dave Cowles (2014): Created original page
CSS coding for page developed by Jonathan Cowles (2007) Salish Sea Invertebrates web site provided courtesy of Walla Walla University

Heptacarpus sitchensis (Brandt, 1851)

Common name(s): Sitka coastal shrimp, Sitka shrimp, Red-banded transparent shrimp, Common coastal shrimp

References: