Diving with Sea Stars, Urchins & Sea Cucumbers

Lanta Marine Life | Echinodermata

Sea Stars, Urchins, Sea Cucumbers, and Feather Stars (Echinoderms) get their name from the Latin for Spiny Skinned - Echinodermata. These animals are abundant and easily spotted when diving around Koh Lanta.

All Echinoderms have radial symmetry; a body construction which points outwards from the centre. This normally consists of more than 5 equal segments, each containing a set of various internal organs.

Sea stars, urchins, sea cucumbers and Feather Stars also have no heart, eye or blood, the function of the blood is replaced by a Water Vascular System. They also have small tentacles called Tube Feet which have suction pads situated at the extremities creating slow hydraulic controlled movement.

Some Echinoderms are planktonic feeders such as the Feather Stars, where as Sea Stars are carnivorous and even like to dine on other Sea Stars.

Echinoderms are mainly nocturnal feeders as to avoid predators which include the Triton Shell, Trigger Fish and some varieties of Crustaceans (Shrimps and Crabs).

Echinoderms have a wonderful ability to regenerate missing limbs, arms, spines and even intestines. Some Brittle stars and Sea stars can reproduce a-sexually by breaking an arm or even splitting the body in half. Each half then form into a whole new animal.

Holothuriidae Sea Cucumbers

Graeffe's Sea Cucumber (Pearsonothuria graeffei)

The Holothuriidae family have thick fleshy bodies, ranging from small to very large, often covered with small rounded projections known as papillae. All species have many tube-like feet on the lower body and several species have 15 - 30 oral tentacles.

Pineapple Sea Cucumber (Thelenota ananas)

Stichopodidae Sea Cucumbers have a squarish cross-section, are flat on the underside, and many members of this family are edible and harvested for restaurants. These sea cucumbers often have prominent, thick, cone-shaped projections on the body, and are found on sand or rubble close the reef edge.

Cushion Sea Star (Culcita novaeguineae )

Many species within this large family are traditional sea stars, usually with 5 arms surrounding a thick, brightly coloured body with a central 'dome' which can often look as though it has been inflated.

Blue Sea Star (Linckia laevigata) @ Koh Haa Lagoon

The Snake Sea Stars are a large family of sea stars, named after the slender members of the genus Ophidiaster, which have snake-like arms. Many species are brightly coloured and patterned, mimicking the appearance of other marine animals which may be poisonous or dangerous for protection.

Common Crown-of-Thorns Sea Star (Acanthaster planci)

Crown-of-Thorns Starfish are disc-shaped, multi-armed starfish, starting life with the typical 5 arms, but growing many more as it matures.

Toxopneustidae Sea Urchins have an internal skeleton (test) made of overlapping plates which form a globular shape. The outer shell of this family are covered with short moveable spines, with tiny pedicellariae (pincers) located between the spines. Some species have a toxic venom within these pincers which is used for defence.

Double-Spined Urchin (Echinothrix calamaris)

Longspine Sea Urchins are a family of around 32 species of spiny, spherical, or globe shaped animals with hard shells which live on the seabed. As with other echinoderms, most Longspine Sea Urchins have a five part symmetry, with five equally sized parts radiating out from their central axes. The mouth is at the base, and the anus at the top.

Blue Tuxedo Sea Urchin (Mespilia globulus)

Temnopleuridae Sea Urchins are a family of around 66 species of spiny, spherical or globe shaped animals with hard shells which live on the seabed. As with other urchins, members of this family have five equally sized parts radiating out from their central axes. The mouth is on the underside, at the base.

Feather stars are found at all coral reefs around Koh Lanta in a range of colours, including black and white, pink, purple, yellow, white and orange. Some species have multiple colours and patterns.

Scuba Diving & Snorkel Trips

If you'd love a chance to spot Sea Stars, Urchins & Sea Cucumbers on one of our daily high season diving trips from Koh Lanta then send us an email to info@diveandrelax.com.

Join our high season speedboat dive trips to some of Thailand's best dive sites and enjoy small groups, short journey times, with a focus on great personal service, safety and fun.

Not yet a certified diver? Learn to Scuba Dive on Koh Lanta with the 3 day SSI Open Water Diver course.

Book online to save 10% on dive trips and scuba courses on Koh Lanta.

Find Out More

Indo-Pacific Marine Life Guides

Allen, G., Steene, R., Humann, P., DeLoach, N. (2003) Reef Fish Identification, Tropical Pacific. Jacksonville, FL., USA: New World Publications, Inc., ISBN 1-878348-36-1.
Humann, P., DeLoach, N., (2010) Reef Creature Identification, Tropical Pacific. Jacksonville, FL., USA: New World Publications Inc., ISBN 978-1-878348-44-9
Debelius, H. (2013) Indian Ocean Reef Guide. Frankfurt, Germany: IKAN - Unterwasserarchiv, ISBN 978-3-939767-52-7.
Debelius, H. (2004) Nudibranchs and Sea Snails, Indo-Pacific Field Guide. Frankfurt, Germany: IKAN - Unterwasserarchiv, ISBN 3-925919-51-1
Erhardt, H., Knop, D. (2015) Corals Indo-Pacific Field Guide. Frankfurt, Germany: IKAN - Unterwasserarchiv, ISBN 3-925919-69-4.
Veron J.E.N., Stafford-Smith M.G., Turak E. and DeVantier L.M. (2016). Corals of the World

More Marine Life References and Further Information

Diving with Sea Stars, Urchins & Sea Cucumbers

Lanta Marine Life | Echinodermata

Holothuriidae Sea Cucumbers

Stichopodidae Sea Cucumbers

Cushion Stars and Allies

Snake Sea Stars

Crown-of-thorns Starfish

Toxopneustidae Sea Urchins

Longspine Sea Urchins

Temnopleuridae Sea Urchins

Feather Stars