Northern Kelp Crab

Scientists have also used the name Epialtus productus for this species.

The crab's appearance puts it into the family Majidae because it looks more like a spider than a crab. Hence P. producta along with other family members are called spider crabs (Rudy et al. 1987; Ricketts et al.1985).

Conservation efforts for P. producta would include making sure that there are plenty of kelp beds around for everyone, including both the farmers and the crabs.

A conservative act that a person can do is to replace the surfgrass he pulls back. After looking throughout a pool that has surfgrass on top, it is critical that one puts it back in place because animals beneath the water need their shade. A person should definitely do this when a P. producta is sited.

US Federal List: no special status

CITES: no special status

Primarily, P. producta is a nocturnal vegetarian. In the low rocky intertidal, the crab can been seen in surfgrass beds eating Nereosystis (bull kelp), Ulva (sea cabbage), and Fucus (rockweed). P. producta will also eat barnacles, mussels, hydroids, and bryozoans when its primary food source, algae, is scarce (Rudy et al. 1987).

Pugettia producta is found within the rocky intertidal shores between Asuncino Point, Baja California all the way up to Alaska (Rudy et al. 1987).

Biogeographic Regions: nearctic (Native )

Pugettia producta can be found in dense kelp beds, and tide pools covered in surfgrass or algae. They can also descend to the depth of 40 fathoms.

Due to its wide range of locations, the temperature range which Pugettia producta can tolerate is somewhat greater than most marine organisms(Ricketts et al. 1985).

Aquatic Biomes: coastal

This particular family of crab has a unique, elongated carapace, looking like an upside down shovel with the handle end towards its mouth. It has four pairs of slender walking legs and a pair of modified legs called chelipeds. Their abdomen has seven segments.

The color of the crab is food-dependent, meaning that the color greatly depends on the type of algae they consume in their surrounding environment. This particular adaptation gives P. producta a natural camouflage. Mostly, the color is dark brown or olive green, but sometimes there is a mixture of the two colors. It can also be reddish orange; however, this coloring is usually found on the ventral side.

The carapace is smooth and not as hairy as the other crabs. Even in its own family, Majidae, Pugettia producta's legs appear to be smoother. Rarely do you see much debris attached to the outer surface. Their eyes are relatively close together compared to other species of crabs outside of its family.

The male has relatively larger chelipeds than the female. The males' legs are also shorter than the females' (Rudy et al.1987; Mohler et al.1997).

Range mass: 0 to 0 kg.

Other Physical Features: ectothermic ; bilateral symmetry

Pugettia producta undergoes a terminal molt upon reaching sexual maturity. Gravid females, June to July, copulate by hard-shelled pairs. Soon, reddish-orange or yellow eggs develop underneath the female's abdomen. It is here that the eggs will stay for several months. Sometimes the eggs will remain for two generations or more before they develop into an adolescent crab (Rudy et al. 1987; Ricketts et al. 1985).

Geographical Range: Chichagof Island, Alaska to Ascuncion Point, Mexico

Depth Range: Intertidal to 73 m

This majid crab can grow fairly large. Its rostrum consists of two flattened processes. The carapace is longer than wide. It has a sharp lateral projection at or behind the middle. The dorsal carapace surface is almost smooth. The distance between the eyes is less than about 1/3 the carapace width. Color greenish brown to maroon dorsally, reddish or yellowish ventrally. Young crabs are brown, red, or olive green. Carapace width to 9.3 cm in males and 7.8 cm in females.

How to Distinguish from Similar Species: Pugettia gracilis does not grow as large, and its dorsal carapace is rough. Scyra acutifrons has a rounder, rougher carapace. The carapace of Hyas lyratus is wider in front, and is also rougher. Cancer productus is a cancer crab

Biology/Natural History: This species does not decorate itself as much as some other majid crabs do. It does have two rows of hooked setae just behind its rostrum, to which it sometimes attaches algae, etc. The items it attaches may be mainly food, which it detaches and eats later. This crab eats algae such as Fucus, Macrocystis, Nereocystis, Sargassum, Egregia, Pterygophora, and red algae. Where algae is scarce they may eat barnacles, mussels, hydroids, and bryozoans. Predators include staghorn sculpins, gulls, cabezon, and sea otter. Velella velella, the by-the-wind sailor, will readily capture and eat the pelagic larvae. The species is sometimes parasitized by the rhizocephalan sacculinid barnacle Heterosaccus californicus, which causes the crabs to be sluggish and to have a brownish mass protruding from under the abdomen. The crab molts only once after being parasitized, and during that molt the barnacle's reproductive sac pushes out through the surface. The crab's gonads are damaged or destroyed and males exhibit some female-like characteristics such as a broad abdomen and small claws. He may even become a hermaphrodite and produce eggs as well as sperm. Females seem less affected other than speeding up the development of mature female characteristics. This species cannot osmoregulate so it cannot tolerate diluted seawater. The species has a terminal molt, after which the carapace may become partly overgrown with barnacles, etc. In the fall adults migrate to deeper water where they congregate, feed, and mate. Females may be carrying eggs during most seasons of the year. In southern Puget Sound females could not be found during May, September, and October. Clutch size ranges from 34,000 to 84,000 eggs. Freshly extruded eggs are bright orange, maturing to red, and to grayish-purple at hatching. Embryonic development may require nearly a year. Note: The long legs and claws of these crabs are dextrous and they can cling tenaciously and pinch hard, so be warned.

Mostly in kelp beds, either on the bottom or climbing in the kelp. Also common on pilings. Juveniles may be in tidepools or around surfgrass or Fucus.