Thelenota rubralineata
A large, red-lined sea cucumber of Indo-Pacific coral slopes.
Thelenota rubralineata is a sea cucumber from the family Stichopodidae, within the phylum Echinodermata. It lives mainly in the central Indo-Pacific, on the seabed near coral. This species belongs to the genus Thelenota, whose members are large and possess a calcareous ring.
Its body is elongated and roughly trapezoidal, measuring 30 to 39 cm long and 8 cm wide when not contracted. Like other Thelenota, it has a clear difference between its upper and lower surfaces. The dorsal side is covered with papillae and pedicels, while the ventral side has many podia scattered randomly. On the back, two rows of 13 to 15 large, conical arms stick out, many ending in spiked papillae. The sides have a continuous row of multipapillate protrusions, with smaller outgrowths scattered elsewhere. The body is patterned with red lines over a white base; near the middle, these lines run parallel and cross to form maze-like designs. The conical protrusions share this pattern, with white-tipped papillae. The podia are pale greenish-yellow, and the twenty tentacles are red.
This species occurs on outer coral reef slopes, among large rubble and coarse sand near islands, at depths of 20 meters and deeper. It is widespread across the Indo-Pacific.
Like other Thelenota, T. rubralineata has calcareous spicules—granules and branched rods—in its body wall, providing support and defense. Two polian vesicles aid locomotion. Five broad, V-shaped longitudinal muscles attach to the body wall. It also has a short digestive tract, two narrow respiratory trees, and a small circulatory system running alongside the intestines. When moving, the lateral protuberances help it walk. If disturbed, it bends its body into a helix, bringing its mouth near its anus, and stays like that for up to 10 minutes or longer before moving again. Its lifespan is unknown, but like other echinoderms, it is thought to regenerate, so lifespan cannot be estimated but is assumed to exceed several decades in the wild.
T. rubralineata and other echinoderms are commonly harvested in the Western Central Pacific, including Micronesia, Polynesia, Melanesia, Australia, and New Zealand. Divers have observed it to be widespread but rarely found in large numbers.
Quick Facts
- Genus
- Thelenota
- Species
- rubralineata
Facts from the source article.
Lore & Background
Thelenota rubralineata has an elongated, roughly trapezoidal body 30 to 39 cm long and 8 cm wide when uncontracted. Its dorsal surface is covered with papillae and pedicels, including two rows of 13 to 15 large conical arms, many ending in spiked papillae. The sides bear a continuous row of multipapillate protrusions, with smaller outgrowths scattered randomly. The ventral surface has numerous podia scattered randomly. The body is covered in a complex pattern of red lines on a white base; toward the middle, these lines run parallel and intersect to form maze-like patterns. The conical protrusions share this pattern, with papillae ending in white peaks. The podia are pale greenish-yellow, and the 20 tentacles are red.
This species is found on outer coral reef slopes with large rubble and coarse sand patches near islands at depths of 20 meters and deeper, and is widespread throughout the Indo-Pacific region. Like other Thelenota, it contains calcareous spicules in the form of granules and branched rods throughout the body wall, providing structural support and defense. Two polian vesicles aid locomotion, and five broad, V-shaped longitudinal muscles attach to the body wall. It has a short digestive tract, two narrow respiratory trees, and a small circulatory system parallel to the intestines. When moving, the lateral protuberances assist in walking. When disturbed, it bends its body in a helical fashion, arranging its mouth close to the anus, and holds this position for up to 10 minutes or longer before moving again. Lifespan is unknown, but like other echinoderms it is suspected to regenerate, and lifespan is assumed to be greater than multiple decades in its natural environment.
Reader's Guide
Thelenota rubralineata is a member of the genus Thelenota, characterized by large size and a calcareous ring. While not one of the most economically profitable species for fisheries, it is commonly harvested alongside other echinoderms in the Western Central Pacific region, including Micronesia, Polynesia, Melanesia, Australia, and New Zealand. Observations by divers indicate the species is widespread but rarely found in large densities. The article notes that this species may become more prone to overfishing due to a reduction in more commonly used species of echinoderms. Its distinctive red-on-white pattern and large size make it recognizable, but its ecological role and population dynamics remain underdocumented. The species' ability to assume a defensive helical posture for extended periods and its suspected regenerative capacity contribute to its resilience, though its exact lifespan is unknown. The presence of calcareous spicules throughout the body wall provides both structural support and defense against predators.
Did You Know?
- Thelenota rubralineata has a body length of 30 to 39 cm and width of 8 cm when uncontracted.
- The species is widespread throughout the Indo-Pacific region but rarely found in large densities.
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