Echinoderms
Sea cucumber
Holothuria sp.
Epipelagic zone · Mesopelagic zone
A true vacuum cleaner of the seafloor, continuously recycling sand and sediment — some species defend themselves by expelling their own internal organs at an attacker.
🗺️ Geographic range
Seafloors of every ocean in the world, from shallow reefs to the great depths.
📊 Population
Highly variable by species and region; several Holothuria species are in severe local decline due to overfishing for the Asian bêche-de-mer market, with no global IUCN assessment for the genus.
⚠️ Threats
Overfishing for the bêche-de-mer market
Several Holothuria species are experiencing severe local decline due to overfishing for the Asian dried bêche-de-mer market.
Source: French National Museum of Natural History
Habitat
- Pacific Ocean · Mesopelagic zone · Permanent
🥚 Reproduction
External fertilisation; also able to reproduce by splitting its own body.
Behaviour
- Diet
- Decomposing organic matter, filtered straight from the sand and sediment.
- Hunting
- None: moves slowly, continuously ingesting and expelling sediment.
- Communication
- None.
- Social life
- Generally solitary.
Physiology
- Anatomy
- A soft, elongated, cylindrical body covered in small papillae.
- Respiration
- An internal respiratory tree connected to the cloaca.
- Vision
- No eyes.
- Adaptations
- Can expel some of its internal organs (evisceration) to repel a predator, then regenerate them.
⚡ Its extraordinary abilities
- Can expel its own internal organs to repel a predator, then regenerate them entirely
- Recycles a considerable amount of marine sediment every year, an essential ecological role
🏆 Records
The only animal known able to expel and then regenerate its internal organs at will
A defence mechanism called evisceration, followed by full regeneration.
If you cross paths with this animal…
Risk: None for humans.
Behaviour: Completely motionless or very slow, does not flee.
Advice: Do not handle — stress can trigger needless evisceration of the animal.
💡 Did you know?
- Can literally empty itself of its internal organs to survive an attack, then regrow them.
- Plays a role comparable to earthworms, but for the seafloor.
