BBSR
Marine Invertebrates of Bermuda

Four sided sea cucumber, Sea pudding
(Isostichopus badionotus)

By Sara K. MacSorley
Dr. James B. Wood

Taxonomy  Habitat  Ecology  Recent Research  Commercial Importance  Bermuda Laws  Personal Interest  References  Links 



Photos By Sara K. Macsorley


Taxonomy


Phylum: Echinodermata
    Class: Holothuroidea
          Order: Aspidochirotida
               Family: Stichopodidae


Abstract

Isostichopus badionotus is a large deposit-feeding sea cucumber found throughout the Caribbean and is very common in Bermuda. As a member of Echinodermata, the sea cucumber has a water vascular system with tube feet, pentaradial body symmetry, a dermal endoskeleton and mutable connective tissue. I. badionotus is a crucial component of the marine food web. As a bioeroder, this species is responsible for mixing the sediment and recycling detritus. Sea cucumbers are gonochoric and have external fertilization. I. badionotus is also commercially important. There is a large fishery in Asian countries where the body wall of sea cucumbers is considered a delicacy.

Habitat


Isostichopus badionotus is widely distributed throughout the Caribbean (Guzman et al. 2002). It is found in epibenthic habitats and is very common throughout Bermuda. It is found mostly on sand, but also is found on bare hard surfaces, rubble, dead coral, pavements, erect macroalgae and turf algae growing on substrates (Hammond 1982). Depth is usually shallow, less than 100 meters. I. badionotus tends to prefer shaded areas (Sterrer 1986). Seagrass meadows are also a common habitat for many Holothurians (Guzman et al. 2002). Though there is no significant data, it is thought based on field observations and the species sluggish nature that individuals remain associated with the same area throughout their lifetime (Hammond 1982, Sterrer 1986). I. badionotus moves very slowly with accompanying changes in length (Hill et al. 1978). Studies by Sloan (1980) showed that the distribution of I. badionotus on the Bermuda platform is primarily related to shelter from wave action and not necessarily depth (Sloan & Bodungen 1980).

Ecology


Anatomy & Morphology: Like all Holothurians, Isostichopus badionotus has an elongate cylindrical body. The body wall is quite thick and leathery, but soft to the touch (Hammond 1982). The body wall is rigid and firm but can deform extremely in response to stress (Hill et al. 1978). This is due to the mutable connective tissue, a synapomorphy of the Phylum Echinodermata (Wood 2006). The mouth is ventral and anus terminal. The body itself is arched dorsally and flat ventrally. There are four series of wart-like papillae on the dorsal surface. The papillae have distinct pedicel ends (Cutress 1996). The characteristic Echinoderm ossicles are microscopic. This species is large, growing greater than 400 millimeters in length (Sterrer 1986). Measurement can be difficult considering their muscles contract distinctively and unpredictably when handled (Hammond 1982). There are two main color patterns of I. badionotus. The most common is a solid dark brown to almost black coloration. The less common is lighter brown with dark brown to black spots or blotches (Sterrer 1986).

Feeding & Predation: Isostichopus badionotus has no form of concealment during the day and remains completely exposed at all times. Even though it can be seen during the day, the sea pudding has markedly nocturnal feeding and activity patterns. In other some related species, nocturnal activity probably evolved as a predator avoidance mechanism, however since the sea pudding is visible during the day this mechanism is probably not the cause of its diel cycles (Hammond 1982). However it is possible that the feeding tentacles are more protected from predators at night. The number of feeding tentacles in I. badionotus increases with increasing size, usually ranging from 16-20 tentacles (Cutress 1996). The major predator of the sea cucumber is fish although there is relatively low predation due to toxins found in the body wall in most tropical Holothurians (Hammond 1982). Sea cucumbers are crucial components of marine food webs. They are sometimes referred to as the earthworms of the sea because they are responsible for the recycling of detritus and mixing of substrate. They feed by taking in sediment and organic matter and grinding it into smaller particles. This breaks up and shuffles the top layer of sediment to allow the penetration of oxygen. This may also help control the populations of marine pests and pathogens in the sediments. I. badionotus can process up to 160 grams of sediment in a 24 hour time period and is estimated that in Bermuda it ingests 500-1000 tons of sediment per year (Bruckner et al. 2003). This species is an unselective feeder with regard to particle size. I. badionotus is the only large deposit feeding Holothurian in Bermuda. In areas where there are co-existing Holothurians, each species tends to ingest different size sediments. I. badionotus possibly occupies so many different habitats in Bermuda due to the lack of co-existing species (Sloan & Bodungen 1980).

In addition to deposit feeding on sediments, I. badionotus is known to partake in cocrophagy or the ingestion of feces. It is not observed often. This action may provide a food source with greater amounts of potential nutrients than ambient sediments. Cocrophagy is often seen in deposit feeders and other sea cucumbers (Sloan & Bodungen 1980). It has also been found that the marine bacterium Pseudomonas atlantica produces a polymer that is a source of nutrition for I. badionotus (Baird & Thistle 1986).

Reproduction: Isostichopus badionotus is gonochoric and has external fertilization. Reproduction occurs throughout the year with periods of enhanced activity. The highest reproduction is observed in the warmest parts of the year; however, salinity may play a more important role than temperature (Guzman et al. 2002). Spawning occurs at dusk. The sea pudding remains in a stationary upright posture throughout the entire spawning event (Hammond 1982). Juvenile sea cucumber are not commonly seen or collected because they have a very cryptic lifestyle (Cutress 1996). Most information on juvenile Holothurian biology is based on laboratory and hatchery raised juveniles. In addition to the cryptic lifestyle, the calcareous spicule arrangement of juvenile sea cucumbers can be drastically different from that of adults which can lead to misidentification. Therefore, little juvenile work is done in the field (Shiell 2004). Juvenile I. badionotus are translucent, yellowish white with reddish brown splotches on the dorsal surface. They have no ventral markings (Cutress 1996). Sexual maturation is estimated to occur when a juvenile reaches 18 centimeters in length and the sex ratio is usually found to be 1:1 (Guzman et al. 2002).

Recent Research


There was a study done in Venezuela determining the concentrations of heavy metals in the bodies of sea cucumbers, Isostichopus badionotus included. It was found that eviscerated tissues of large individuals have significantly higher metal concentrations than those of smaller individuals. I. badionotus tissues had higher concentrations than those of Holothuria mexicana, the other main species in the study. Both sea cucumbers showed values higher than that of other marine invertebrates in the area and deep water sea cucumbers. The importance of this study lies with the fact that the levels were higher than the legal reference and maximum recommended values. This might pose a public health risk considering the sea cucumber fishery (Laboy-Nieves & Conde 2001).

Commercial Importance


Over 30 species of sea cucumbers, especially members of the families Holothuridae and Stichopodidae, are part of a large invertebrate fishery. They have been sought after for over 1000 years (Bruckner et al. 2003). The Asian food market is proving a reason for increased fisheries management of Isostichopus badionotus (Guzman et al. 2002). The exact effects on I. badionotus are not known because the individual species of sea cucumber are rarely differentiated in trade reports. There is substantial information on the main markets and trade routes, but there is a lack of information regarding the location and volume of harvest. The central markets are in Hong Kong, Singapore and Chinese Taipei (Bruckner et al. 2003).

Some species of Holothuridae, not I. badionotus, may soon qualify for a listing on the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). The sea cucumbers are susceptible to overexploitation in fisheries due to their biology, population dynamics, and habitat preferences such as late maturity, density-dependant reproduction and low rates of recruitment (Bruckner et al. 2003). There have been advances in rehabilitation programs for sea cucumber populations affected by overfishing. The idea is to raise juveniles in hatcheries and release them into the wild (Shiell 2004). More data, studies and collaboration between scientists and industry leaders is needed.

Some species of sea cucumbers are used in aquaria and areas of biomedical research (Bruckner et al. 2003).

Bermuda Laws


There are no laws involving Isostichopus badionotus in Bermuda at this time.

Personal Interest


Ever since I learned that sea cucumbers could expel their internal organs and regenerate them, I was hooked. Regeneration has long been a fascination of mine, whether in flatworms, sponges, sea stars or sea cucumbers. Isostichopus badionotus became of particular interest after my first snorkel here in Bermuda. I have seen them almost every time I have been underwater here, especially on the night dive as they crawled slowly across the bottom. Then in Marine Invertebrate Zoology we learned about how Echinoderms have mutable connective tissue. If stroked too much I. badionotus can go from having a rigid body wall to a pile of mush and it’s still alive!! We simple humans are not capable of throwing up our digestive system or turning to mush while being able to completely recover and we think we're so all mighty. The big brown sea puddings may not look like anything exciting when you see them underwater, but they have more going for them than you think.

References

Bruckner, A. W., Johnson, K. A., Field, J. D. 2003. “Conservation strategies for sea cucumbers: Can a CITES Appendix II listing promote sustainable international trade?” SPC Beche-de-mer Info. Bull. 18.

Baird, B. H., Thistle, D. 1986. "Uptake of bacterial extracellular polymer by a deposit-feeding holothurain (Isostichopus badionotus). Mar. Bio. 92:183-187.

Cutress, B.M. 1996. “Changes in Dermal Ossicles During Somatic Growth in Caribbean Littoral Sea Cucumbers (Echinoidea: Holothuroidea, Aspidochirotida)”. Bull. Mar. Sci. 58: 44-116.

Guzman, H. M., Guevara, C. A., Hernandez, I. C. 2002. “Reproductive Cycle of Two Commercial Species of Sea Cucumber (Echinodermata: Holothuroidea) from Caribbean Panama”. Mar. Bio. 142: 271-279.

Hammond, L. S. 1982. “Patterns of Feeding and Activity in Deposit-feeding Holothurians and Echinoids (Echinodermata) from a Shallow Back-reef Lagoon, Discovery Bay, Jamaica”. Bull. Mar. Sci. 32: 549-571.

Hill, R. B., Sanger, J.W., Yantorno, R.E., Deutsch, C. 1978. “Contraction in a Muscle with Negligible Sarcoplasmic Reticulum: the Longitudinal Retractor of the Sea Cucumber Isostichopus badionotus (Selenka), Holothuria Aspidochirota”. J. Exp. Zool. 206: 137-150.

Laboy-Nieves, E. N., Conde, J. E. 2001. "Metal levels in eviscerated tissue of shallow-water deposit-feeding holothurians." Hydrobiologia. 459:19-26.

"sarcoplasmic reticulum." Dictionary.com Unabridged (v 1.0.1). Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006. 06 Nov. 2006.

Shiell, G. 2004. “Field observations of juvenile sea cucumbers.” SPC Beche-de-mer Info. Bull. 20.

Sloan, N. A., Bodungen, B. 1980. "Distribution and feeding of the sea cucumber I. badionotus in relation to shelter and sediment criteria of the Bermuda platform. Mar. Ecol. Prog. Ser. 2:257-264.

Smith, C. L., Tyler, J. C. 1969. “Observations of the Commensal Relationship of the Western Atlantic Pearlfish, Carapus bermudensis, and Holothurians”. Copeia. 1969: 206-208.

Sterrer, W. 1986. Marine Fauna and Flora of Bermuda. 537-540.

Links


Smithsonian
Wikipedia