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2005 California Academy of Sciences
CalPhotos
30mm long - on a gorgonian, Lophogorgia from 58 m deep Female brooding eggs
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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.
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This closeup of the carapace shows the short rostrum which extends past the cornea but not past the first article of the first antenna, with 3-6 stout dorsal spines (some on the carapace), a single tip, and no ventral spines, and no supraorbital spine.
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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 multiarticulatedcarpus. Pereiopods 3-5 are similar to one another but in this species their dactyl (tip) is bifid.
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This individual shows another color phase. This shrimp has a very strange history and shows that this species is capable of a stygian lifestyle. The shrimp was found living at the bottom of the Rosario Beach Marine Lab seawater reservoir when it was opened for inspection in June 2012. The seawater pumps had been shut off since August 2011. This shrimp and a number of others in the tank must have been sucked through the intake filter screens as larvae in August 2011 at the latest. They would have had to have grown to full size in the underground seawater reservoir through the 10 winter months of 2011-2012, in total darkness and in uncirculated seawater. Presumably they ate debris off the bottom of the tank. The light for this photo is likely some of the first light this shrimp has ever seen. Carapace length for this individual is about 9 mm and total length is 3.5 cm. Photo by Dave Cowles, June 2012
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2005 California Academy of Sciences
CalPhotos
Closeup of compound eyes of this shrimp. The specimen was brought up by a diver from 58 m depth.
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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 multiarticulatedcarpus.
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The posteroventral corner of the pleurons on abdominal segments 4 and 5 have a sharp point on this species. Photo by Dave Cowles, June 2012
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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.
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This species has an epipod on pereopods 1-3. This photo shows the coxae at the base of the right pereopods 2 (on the left) to 4 (on the right) The edge of the carapace can be seen above the legs. The flaplike epipod can be seen projecting to the right from the dark part of the coxa of pereopod 2 just above the center of the photo. Photo by Dave Cowles, June 2012.
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This view of the propodus and dactyl on pereiopod 4 clearly shows the bifid tip of the dactyl.
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Dactyls of pereopods 3-5 are bifid (forked at the end). Photo by Dave Cowles, June 2012.
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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.
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Heptacarpus brevirostris from Padilla Bay. Total length approximately 5 cm. Identified by Andrew Geigle. (Photo by: Dave Cowles, July 2006)
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Heptacarpus sitchensis has a pterygostomial spine at the anteroventral margin of the carapace, seen here just below the base of the 2nd antenna.
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The ventral margin of abdominalpleuron 4 (middle-right) of this species has a spine. Abdominalpleuron 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".
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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.
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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).
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Heptacarpus sitchensis, two individuals about 2 cm long. Collected intertidally from the N Oregon coast. (Photo by: Dave Cowles, April 2014)
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