Apostichopus californicus (Stimpson, 1857)

Common name:  California Sea Cucumber, giant sea cucumber

Stichopus californicus, Holothuria californica, Parastichopus californicus
Adult P californicus
Phylum Echinodermata
 Class Holothuroidea
   Order Aspidochirotida
     Family Stichopodidae
Apostichopus californicus Found in Rosario Bay, WA.  Side view.  Animal is approx. 45 cm in length.
Photo by: Dave Cowles, July 2020
Description:  Large sea cucumber ranging from 25 to 40cm in body length.  Dorsal and lateral surfaces dark red, brown, or yellow.  The body surface bears large, stiff, conical papillae or pseudospines.  Papillae are usually paler in color than body surface and tipped with red.  Tube feet are densely arranged on the ventral side and only three pairs of rows of tube feet are distinct.  The mouth is directed ventrally at the anterior end (photo) and is surrounded by tentacles.  Length to 50 cm.

How to Distinguish from Similar Species: Apostichopus parvimensis, which lives from Monterey Bay south, is very similar in form and can grow to nearly as large, but the body is chestnut brown dorsally and much paler below; plus the tips of its papillae are tipped with black instead of red.  Parastichopus leucothele is colored similarly but lives at deeper depths (24-285 m) and is colored bright orange with rusty brown patches and small white papillae.

Geographical Range:  From the western Aleutian Islands and Bering Sea off Alaska to Baja California

Depth Range:  Low intertidal zone to 90 m deep

Habitat:  Exposed and sheltered areas protected from strong wave action.  Subtidal species are found primarily on gravel and shell debris

Biology/Natural History:  P. californicus is the largest sea cucumber species along the Pacific Northwest coast.  The species feeds on organic detritus and small organisms, which it ingests with bottom sediments.  The primary predators of P. californicus are the sea stars Pycnopodia helianthoides and Solaster endeca, but the species is also occasionally eaten by sea otters and man.  Unlike many tropical sea cucumbers, P. californicus does not store substances toxic to predators.  The hindgut bears a pair of highly branched diverticula, which project into the coelomic cavity of the body and serve as “water lungs”.  Oxygenated water is pumped into these respiratory trees in several successive inhalations and then expelled in one powerful exhalation.  Breeding occurs in the summer.  Development is indirect.  The sperm have spherical heads and an unusually low DNA content.  The fertilized eggs develop into auricularia larvae which metamorphose into doliolaria larvae which settle.  The pelagic phase lasts from 7 to 13 weeks in the laboratory.  Like many sea cucumbers, this species is capable of eviscerating much of its internal organs when disturbed (photo). Populations of P. californicus in the Puget Sound also lose and then re-grow nearly all their internal organs during October and November and then regenerate new sets of organs, but this process does not appear to involve evisceration.  Evisceration may also occur if the animals are kept in warm or stale water.  The scale worm Arctonoe pulchra may occur as a commensal on P. californicus

Recently this species has been discovered to be able to take up nutrients via the respiratory tree in the anus.  Brothers et al. (2011) found that labeled stable isotopes from the seawater made their way into the cucumber through the anus and respiratory tree, especially in late winter/early spring when the animal was regenerating its gut.  Jaeckle and Strathmann (2013) found that radiocarbon-labelled unicellular algae and iron-containing macromolecules could also be incorporated into animal tissues via the respiratory tree.

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Dichotomous Keys:
  Carlton, 2007 
  Kozloff, 1987

General References:
  Lamb and Hanby, 2005 
  Lambert, 1997
  Morris, Abbott, and Haderlie, 1992. 
  Kozloff, 1993. 
  O'Clair and O'Clair, 1998 

Scientific Articles:

Brothers, C.J., J. R. Nestler, and R.W. Lee, 2011.  Visceral regeneration by the uptake of dissolved organic material in the sea cucumber Parastichopus californicus.  Abstract, 6th North American Echinoderm Conference, Anacortes, WA.

Jaeckle, William B. and Richard R. Strathmann, 2012.  The anus as a second mouth: anal suspension feeding by an oral deposit-feeding sea cucumber.  Invertebrate Biology 132:  pp 62-68

McEdward, Larry R. and Benjamin G. Miner, 2006.  Estimation and interpretation of egg provisioning in marine invertebrates.  Integrative and Comparative Biology 46:3 pp 224-232

Woodby, D., S. Smiley, and R. Larson, 2000.  Depth and habitat distribution of Parastichopus californicus near Sitka, Alaska.  Alaska Fishery Research Bulletin 7: 22-32

General Notes and Observations:  Locations, abundances, unusual behaviors, etc.:

Another photo of Apostichopus californicus.  This species can become short, round, and turgid or long, limp, and flaccid.  Photo by Dave Cowles, July 1997

On June 22, 2005 divers from the station gathered 5 A. californicus for an experiment.  All five were placed into the same running seawater tank, measuring 170 x 48 x 120 cm.  Within a few hours (about sundown) four of the five cucumbers began releasing gametes into the water.  All gametes released were in a thin, wispy white stream which looked like sperm.  They continued releasing gametes until the tank, though it was being gently flushed with seawater, was cloudy.  Gamete release continued for at least half an hour.  The day before (June 21) had been the full moon.  Below I have a still photo, plus a link to a digital movie of gamete release by the cucumbers.

Gametes being released by Apostichopus californicus. Photo in the lab by Dave Cowles June 22, 2005.

Here is a link to a digital .MPG movie of Apostichopus releasing gametes on June 22, 2005.

This individual is feeding on the sediment near Rosario.  Photo by Jim Nestler, July 2005 

As with many sea cucumbers, Apostichopus californicus can dramatically change the rigidity of its body, both by adjusting muscle tension and by actually changing the flexibility of its skin. The sequence below shows a sequence of changes in the morphology of an individual as I hold it, going from an initially rigid posture to very relaxed, stretched, and flexible. Photos by Dave Cowles, July 2020
Originally rigid
Initially upon capture most individuals hold their bodies rigid. This individual is just beginning to relax a little. View is of the dorsal side.
After a minute or two of holding without disturbance, the individual begins to relax more. In this view I have slightly turned the individual as well so the ventral rows of tube feet can be seen.
Within a few minutes the animal becomes very relaxed and droopy, both by changing the flexibility of its skin and by releasing some of the water from its anus. Often most of the internal mass seems to flow to one side or the other, making one side (often anterior) heavier and causing the animal to slip out of my grip and fall to the ground. This view is also primarily of the ventral side with the tube feet.


A small individual about 14 cm long. Photo by Dave Cowles, July 2020

Oral tentacles
The moplike oral tentacles, characteristic of Order Aspidochirotida, with which they feed on benthic sediment can be seen through the aquarium glass as this individual attempts to feed. Photo by Dave Cowles, July 2020

Abstract from Kari McCloskey MS thesis, Department of Biology, Walla Walla College, May 2006:

Diel and Seasonal Cycles of Movement, Metabolism, and Nutrient Excretion by the Temperate Holothurian Parastichopus californicus

Sea cucumbers (Phylum Echinodermata, Class Holothuroidea) influence ocean communities by affecting physical and chemical characteristics of water and sediment through their deposit feeding and excretion activities.  Several tropical species of sea cucumbers exhibit daily cycles of behavior and physiological processes, though research on this phenomena in temperate waters is limited.  Seasonal cycles of behavior and physiological processes have also been observed to occur among temperate and tropical species.  Daily and seasonal movement rates, metabolism, and nutrient excretion were measured for the temperate sea cucumber Parastichopus [now Apostichopus] californicus.  Daily differences in phosphate excretion were noted for P. californicus during the summer, with significantly greater concentrations recorded at night than during the day.  No day vs. night differences were observed for movement, metabolism, or ammonium excretion by P. californicus in either summer or winter.  Movement rate and the concentration of excreted phosphate were significantly lower during winter than in the summer.  Metabolic rate however, was significantly greater during the winter compared to the summer.  Animal size varied seasonally, with mass and volume during the winter being significantly less than in the summer.  These data suggest that some behavioral and physiological process of P. californicus may occur over daily and seasonal cycles, while others do not.
Oral tentacles in situ Oral tentacles in tank
The moplike tentacles are visible in this feeding individual.
Underwater photo by Kirt Onthank, July 2007
This individual in the lab is exploring its tank, reaching up and sweeping its oral tentacles across the water surface. Photo by Dave Cowles, August 2022

This individual eviscerated its gut and respiratory tree after being held a few minutes July 6, 2010.  Photo by Dave Cowles

Authors and Editors of Page:
Kelly Williams (2002):  Created original page
Edited by Hans Helmstetler 12-2002; Dave Cowles 2005-