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Facts and Information about Sea Cucumbers

[Kingdom: Animalia] [Phylum: Echinodermata] [Subphylum: Echinozoa] [Class: Holothuroidea]

Scientists believe tropical sea cucumbers are helping with the global fight against harmful climate change and may reduce the damage that it causes to coral reefs.

This segment contains fun and interesting facts about the sea cucumber species, including where they thrive best, what they eat, and how these holothurian marine invertebrates reproduce.

Where Do Sea Cucumbers Live in the World

Holothuroidea is a classification within the phylum Echinodermata that contains around 1,200 different species of sea cucumbers.

So, where are sea cucumbers found in large numbers? They live in the benthic zones of most tropical and subtropical oceans, especially:

Scuba divers and snorkelers often spot them embedded in the sand or on silty sediment on the seafloor, often crawling between coral reef gardens and other solid habitats, such as rock or boulder outcrops.

Sea Cucumber Characteristics

Unlike most marine creatures, sea cucumbers are sloth-like scavengers that slowly roam around searching for food scraps on the sea bed.

When they feed, they ingest small particles of sand to break down detritus and other organic matter and process it inside their gut.

Here's the thing:

They use bacteria to decompose their food. As a consequence of that, this digestion process creates sea cucumber poop (faeces) that help to increase the potential of hydrogen (pH levels) around the reef.

When different types of sea cucumber defecate, the positive effect for the water may help coral reef polyps combat the negative effects of global climate change. Thus, soft-bodied sea cucumbers are helping to reduce harmful high levels of acidity in the oceans.

The cylindrical body, often warty in appearance, can be as little as two centimetres long and less than a centimetre thick, or it can be up to two metres long (6 feet) and measure twenty centimetres round (8 inches).

How Do Sea Cucumbers Help the Ocean?

There is another benefit from the waste, calcium carbonate. Scientifically known as CaC03, calcium carbonate is an important component for the survival of the reef. This is because corals need to accumulate high levels of CaC03.

Sea cucumbers, along with other tropical "bioeroders" (e.g. sea urchins, marine worms, and chitons), are foremost contributors to the essential turnover of calcium carbonate.

When sea cucumbers digest the food, they also produce ammonia - which helps to fertilise the near vicinity. It also provides important nutrients which, in turn, encourage coral formation.

Benefits of Sea Cucumber Taxonomy

There are more than one thousand different species of sea cucumber that exist in the oceans, and they all have an important role to fulfil underwater.

Sea Cucumber Facts and Species Information with ExamplesFor example, the poop of the amber fish sea cucumber has benefits for aquatic ecosystems. It has a crown of tentacles that it uses to pick up sediment and stuff it into its mouth.

This sea cucumber phylum is renowned for digesting organic material and discarding everything else.

So, what comes out is actually cleaner than when it went in!

The "cleaner" sand helps to prevent algal blooms, which can cause fish to suffocate due to a lack of oxygen.

Furthermore, subtropical seagrass beds seem to grow healthier if sea cucumbers are living in the area. Therefore, coral reefs benefit from the alkalinity of the droppings from sea cucumbers by "buffering" them from the effects of ocean acidification.

Fun Fact: We were wondering what a group of sea cucumbers is called? To our surprise, the collective noun is a prickle of sea cucumbers.

Different Types of Sea Cucumber

Actinopyga Caerulea

Blue sea cucumber

Actinopyga Echinites

Deep water redfish

Apostichopus Californicus

The giant red sea cucumber is one of the heaviest of the species, with some specimens weighing up to one (1) kilogram (2.2 pounds).

Apostichopus Japonicus

Actinopyga Miliaris

Its common name is the hairy blackfish. But, these sea cucumbers belong with the family Holothuriidae, of the Phylum Echinodermata (meaning spiny skin).

Geographical Distribution

For the most part, Actinopyga miliaris is superabundant in the tropical West Indo-Pacific region, where it is often collected and harvested commercially for food.

Facts about the Hairy Sea Cucumber (Actinopyga miliaris)Nonetheless, the species also thrives around shallow coastlines and coral reef ecosystems in:

  • Africa (including the Red Sea)
  • French Polynesia
  • Northern Australia
  • South East Asia (SEA)
  • Western Pacific Ocean

The hairy blackfish prefers to live around shallow rubble deposits and fringing reefs. Thus, it would be rare to see it deeper than twenty (20) metres (70 feet).

Size and Characteristics

Actinopyga miliaris is one of the biggest species of sea cucumber. The hairy blackfish can grow up to thirty (30) centimetres long (14 inches) with a sausage-shaped body measuring around ten (10) centimetres in diameter (4 inches), and a rough, almost leathery, body wall that can be nine (9) millimetres wide.

It's common to see mucus and fine sediment covering the black bivium (face dorsal) and the conical fleshy projections (papillae) running along its elongated, cylindrical body. It also has five strong, triangular shaped anal teeth surrounding its anus.

Conservation Status

Unlike some of the smallest sea cucumbers still in existence, such as Psammothuria ganapati that grows no more than four millimetres long, hairy blackfish are easy to collect by hand and often exploited for commercial use.

Pro Tip: The IUCN Red List of Threatened Species last assessed Actinopyga miliaris in 2010 and cited it as being "Vulnerable" (VU) with the population trend "decreasing".

Bohadschia Argus

Leopard sea cucumber

Colochirus Robustus

Robust sea cucumber

Holothuria Floridana

Florida sea cucumber

Holothuria Fuscogilva

White teatfish

Holothuria Nobilis

Black teatfish

Holothuria Scabra

Orange-Footed Sea Cucumber

Purple Sea Cucumber

Pictures of a purple elasipodida (class holothurian) show the animal using numerous appendages to crawl on the silty seafloor around 900 metres below the surface (3,000 feet).

The international research team filmed it around the base of some undersea mountains (seamounts) near the Galápagos Islands, a famous archipelago in Ecuador.

Using high-resolution sonar imaging, they captured important information about the "Galápagos Platform" and diverse communities of fish, sea sponges, and deep coral structures in this part of the Eastern Pacific Ocean.

Snot Sea Cucumber

Strawberry Sea Cucumber

Synapta Maculata

The snake sea cucumber is the largest sea cucumber with some examples growing to three (3) metres in length (10 feet).

Thelenota Anax

Amber fish sea cucumber

Related Information and Help Guides

Pro Tip: The main section contains even more echinoderm facts and species information with examples of the five living classes still in existence today.

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