Holothuria tubulosa
Type species of genus Holothuria, found in the Mediterranean and eastern Atlantic.
Holothuria tubulosa, also called the cotton-spinner or tubular sea cucumber, belongs to the family Holothuriidae. It serves as the type species for the genus *Holothuria* and is classified within the subgenus *Holothuria*, giving it the full scientific name *Holothuria (Holothuria) tubulosa*.
This sea cucumber reaches lengths between 20 and 45 centimeters, with a diameter of about 6 centimeters. Its body is roughly cylindrical, with a flattened underside bearing three lengthwise rows of tube feet. The skin is tough and leathery, typically brown, and covered with many dark, conical, thorn-like bumps called papillae. The animal often appears grayish because it secretes a protective mucus film that attracts bits of seaweed and sediment. At the front end, a fringe of short, flattened tentacles surrounds the mouth, while the anus is at the rear.
The species lives in temperate parts of the eastern Atlantic Ocean, ranging north to the Bay of Biscay, and is abundant in the Mediterranean Sea. It inhabits sandy seabeds, seagrass meadows (especially *Posidonia* species), and muddy rocks down to depths of about 100 meters.
Feeding on detritus, algae, and plankton, *Holothuria tubulosa* moves across surfaces or clings to rocks using its tube feet. Individuals are dioecious—either male or female—but look identical externally. During a mass spawning event observed in the Mediterranean in August 2003, spawning occurred on two afternoons coinciding with the full moon. Many mature animals reared their front ends upward, leaving only the rear third of their bodies on the seabed. This lifted their genital openings, located just below the mouth, away from the substrate to improve gamete dispersal. First, some individuals (likely males) released a whitish fluid that spread through the water. Then, fewer individuals (likely females) emitted a thicker fluid, possibly triggered by the male gametes. Each release lasted about 30 minutes. The key conditions for spawning appeared to be a full moon and a sea temperature around 25 °C.
Fertilized eggs hatch in about 24 hours, and the larvae drift as plankton. They feed on microscopic algae, passing through several developmental stages over a few weeks before settling on the seabed and transforming into juveniles.
Quick Facts
- Taxon
- Holothuria tubulosa
Facts from the source article.
Lore & Background
Holothuria tubulosa grows to a length of between 20 and 45 cm, with a diameter of 6 cm. It is roughly cylindrical with a flattened base bearing three longitudinal rows of tube feet. Its tough, leathery skin is generally brown and covered with numerous dark, conical, thornlike projections called papillae. It often appears greyish due to a protective mucus film to which bits of seaweed and sediment may adhere. It has a fringe of short, flattened tentacles around the mouth at the anterior end and an anus at the posterior end.
It is found in temperate regions of the eastern Atlantic Ocean as far north as the Bay of Biscay and in the Mediterranean Sea, where it is abundant. It inhabits sandy seabeds, among seagrass (Posidonia spp.), and on muddy rocks to a depth of about 100 m.
Holothuria tubulosa feeds on detritus, algae, and plankton, using its tube feet to move or adhere to rocks. It is dioecious, with no external difference between sexes. A mass spawning event was observed in the Mediterranean in August 2003, coinciding with the full moon and a sea temperature of about 25 °C. Individuals reared their anterior ends, leaving only the hind third in contact with the seabed, to release gametes. Males emitted a whitish fluid, followed by females releasing a more viscous fluid, each release lasting about 30 minutes. Fertilized eggs hatch in about 24 hours, and the planktonic larvae feed on microscopic algae before settling and metamorphosing into juveniles.
Reader's Guide
Holothuria tubulosa is notable as the type species of the genus Holothuria and is placed in the subgenus Holothuria. It is abundant in the Mediterranean Sea and temperate eastern Atlantic, where it occupies sandy and seagrass habitats. Its biology includes a mass spawning event tied to the full moon and a sea temperature of about 25 °C, observed in August 2003. The species is dioecious, with spawning behavior that raises the genital orifices for gamete dispersal. Along with Parastichopus regalis, it is the preferred host of Carapus acus, a commensal fish. Commercially, it is fished in Turkey, with a closed season in August and September to allow spawning. Divers can collect 2000 to 3000 individuals in a day, which are sun dried, oven dried, or frozen for export. The species is used for food in Taiwan, China, Singapore, and Korea, and has been investigated as a source of omega-3 and omega-6 fatty acids and bioactive peptides. Its significance lies in its ecological role, commercial value, and potential pharmaceutical applications.
Frequently Asked Questions
What is Holothuria tubulosa?
It is a cylindrical sea cucumber commonly called the cotton-spinner or tubular sea cucumber, a member of the family Holothuriidae. Its tough, leathery brown skin is studded with dark conical spines, and the flattened underside carries three lengthwise rows of tube feet.
Where does Holothuria tubulosa live?
This species inhabits sandy seabeds, Posidonia seagrass beds, and muddy rocky areas across the temperate eastern Atlantic and the Mediterranean Sea. It occurs at depths up to roughly 100 meters, ranging as far north as the Bay of Biscay.
How large does Holothuria tubulosa grow?
Adults typically measure between 20 and 45 centimeters in length with a body diameter of about 6 centimeters, making it a moderately sized member of the Holothuriidae.
What does Holothuria tubulosa feed on?
It is a detritus scavenger that picks up organic debris from the seafloor, supplementing its intake with algae and plankton. This mixed diet lets it exploit a broad range of food sources on sandy and muddy substrates.
Why is Holothuria tubulosa significant in taxonomy?
It serves as the type species for the entire genus Holothuria, anchoring the classification of every other species placed in that group. Its full trinomial designation, Holothuria (Holothuria) tubulosa, reflects its placement within the subgenus Holothuria.
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