Neotrypaea californiensis
bay ghost shrimp

Neotrypaea californiensis can be found at intertidal locations within the regions of the North American West Coast ranging from Mutiny Bay, Alaska to Tijuana River, San Diego County, California and El Estuario de Punto Banda, Baja California Norte, Mexico. (MacGinitie, 1934; Ricketts and Calvin, 1968)

Neotrypaea californiensis live as infauna in intertidal areas between the middle to low intertidal zones, on sandy beaches or tidal flats in estuaries. Ghost shrimp habitat is distinguished by numerous holes that are the entrances and exits of their burrows. Ghost shrimp are constantly excavating complex tunnels under the sand. (MacGinitie, 1934)

Although the majority of time is spent building tunnels, ghost shrimp do come to the surface at times, where predation can occur. (Posey, 1985)

Body coloration ranges between shades of orange, pink, and red. Some individuals may also exhibit a very pale coloration, almost white. The main body parts of Neotrypaea californiensis follow a generalized decapod body plan: two differently-shaped claws (with one major cheliped, often several times larger than the opposite claw); five pairs of legs, three paddle-shaped swimming legs (pleopods), a fan-like tail (uropod), telson, flattened eyestalks, and two pairs of antennae. The exoskeleton is fringed with numerous fine hairs. (MacGinitie, 1934)

Females bearing eggs carry them on their abdomen. The egg mass may vary in color between individuals, from light yellow to deep scarlet. The major cheliped is sexually dimorphic, being larger on males. The major cheliped can account for up to a quarter of a ghost shrimp's weight. (Labadie and Palmer, 1996)

Neotrypaea californiensis matures between 18 and 24 months. Mature individuals can be found closest to the ocean and they grow much faster compared to individuals located nearer to shore. Larger sized females with larger eggs can be found within intertidal areas.

Females carry their fertile eggs on their abdomen and the eggs are released in June or July. The newly released ghost shrimp larvae (zoea) drift for six to eight weeks in the water column as zooplankton, passing through five zoeal stages before transforming into a megalops. There zoeal stages take place over 6 to 8 weeks. They will return to estuarine habitats as megalopae on flood tides during August. (Bird, 1982; MacGinitie, 1934; McCrow, L.T., 1972)

Using olfactory receptors on their antennules called aesthetascs, a male ghost shrimp detects water soluble substances released by premolt females. Once a female is found, the male will follow and protect her from predators and other suitors with his major cheliped, until she molts. This process is known as temporary mate guarding. After the female molts, the male mates with her and then leaves her to find another premolt female. (Bauer, 2011; Labadie and Palmer, 1996)

Though the mating behavior of the ghost shrimp is largely unknown, it is agreed that the males use the major cheliped to fight other males for reproductive access to females.

The female will carry her brood of eggs for approximately 3 to 5 months. Hatching occurs in June or July. The newly released ghost shrimp larvae (zoea) drift for six to eight weeks in the water column as zooplankton, passing through five zoeal stages before transforming into a megalops. They will return to estuarine habitats as megalopae on flood tides during August. (Horning, et al., 1989; Labadie and Palmer, 1996)

Ghost shrimp reproduce seasonally. The female will carry her brood of eggs for approximately 3 to 5 months until they hatch, usually in June or July. (Horning, et al., 1989)

Ghost shrimp in the wild have an average lifespan of 3-5 years. The primary factor affecting lifespan is the level of available nutrients. Nutrient availability is directly related to the distance of the colony to an estuary. Longer-lived shrimp are found closer the mouth of an estuary. (Bird, 1982; Dumbauld, et al., 1996)

Water temperature and substrate characteristics can also influence shrimp activities, as colder temperatures reduce shrimp mobility and sandy sediments reduce its ability to burrow.

Ghost shrimp in general are constantly burrowing to obtain food. (Horning, et al., 1989; Pernet, B., Deconinck, A., and Haney, L, 2010; Wicksten, 2008)

Ghost shrimp conduct their daily activities within a relatively small circumscribed area. Under experimental conditions, ghost shrimp spent over 25% of the time within 2 cm of the burrow entrance; furthermore, the shrimp were also observed to move from one burrow to another. (Posey, 1985; Wicksten, 2008)

Ghost shrimp territory is limited to a few cm within the vicinity of their own burrow, which they defend from rivals. Population size can be very dense with burrows directly adjacent to those of conspecifics. In Oregon, densities have been estimated at 700-1,400 per square meter in Yaquina bay; 420-770 per square meter in Sand Lake Estuary, and less than 300 per square meter along the coast. (Bird, 1982; McCrow, L.T., 1972)

Tactile: This species uses its antennae, chelipeds, and sensory hairs (called cuticular mechanoreceptors, covering most of the body) to sense physical objects in the environment.

Vision: Eyestalks are acute with divergent tips, and bear a pigmented cornea in the middle of the eyestalk. (Nau, 2004)

Ghost shrimp ingest plankton and detritus deposits scraped from the sediments during burrowing. Plankton is also obtained as water and detrital materials pass over the body and are collected on the hairs of their second and third walking legs. (Nau, 2004)

To find enough food, ghost shrimp tunnel almost constantly, reworking the sediment to a depth of as much as 76 cm. (Horning, et al., 1989)

Although ghost shrimp typically inhabit deep burrows, they are susceptible to predation because they sometimes venture outside of their burrow entrances. Fishes and invertebrates are significant predators when the tide is high, whereas shorebirds and humans prey on ghost shrimp when the tide is low. Shorebirds that feed on ghost shrimp include the long-billed curlew Numenius americanus and the willet Catoptrophorus semipalmatus. Some fish predators include the Pacific staghorn sculpin, Leptocottus armatus. (Light, S., Carlton, T, 2007; Posey, 1985; Posey, M. H, 1986; Stenzel, L., Huber, H., and Page, P, 1976)

The vigorous burrowing activities of ghost shrimp have such dramatic effects on their habitats of soft sediment that these animals are often considered ecosystem engineers. By aerating the surface sediment through burrowing, the ghost shrimp provide an environment attractive to other species including the blind goby, three species of pea crabs, two species of clams, a copepod, a shrimp, polynoid worms, and isopods, all of which live within the burrows. (Horning, et al., 1989; Pernet, B., Deconinck, A., and Haney, L, 2010)

Neotrypaea californiensis is used as live bait by fishermen. Fishermen commonly call them one-armed bandits because of their one long cheliped. (Nau, 2004)

No known negative economic importance for humans.

Neotrypaea californiensis is tolerant of low oxygen conditions, and laboratory results indicate this species can survive anoxic conditions for as long as 3 days. (Thompson and Pritchard, 1969)