How Big Are Sea Cucumbers? (What’s The Largest One?)

Sea cucumbers are fascinating marine animals that may differ in appearance, body structure, size, and weight. There are about 1,250 sea cucumber species, and many are probably still not discovered. If you wonder how big the sea cucumbers get and what’s the largest sea cucumbers, in this blog post, we’ll talk all about that. However, let’s begin with a quick answer:

Sea cucumbers size varies a lot depending on the species and can range from 0.8 in (2 cm) to over 10 feet (3 m) in length. The largest sea cucumber ever recorded was the snake sea cucumber, with 10 feet (3 m) in length, and the smallest was Thyonina bijui with just 0.8 in (2 cm).

However, this certainly doesn’t tell the whole story. Below, I’ll explain more about the largest and the smallest sea cucumber species that were found. Furthermore, I’ll explain how much sea cucumbers can weigh. Read on!

The largest sea cucumbers

Giant red sea cucumber (Parastichopus californicus)

Giant red sea cucumbers are long and cylindrical and can grow up to about 2 ft (60 cm) and weigh up to 2.2 Lb (1 kg). This makes them the largest sea cucumbers of approximately 30 sea cucumber species in British Columbia, west coast of Canada.

Giant red sea cucumbers are red to reddish-orange in color and covered with characteristic pale-colored bumps. In front of their body, they have 20 feeding tentacles, which they use to capture food. They mainly eat dead animals from the seafloor, plankton, algae, and decaying organic matter.

Where they live: Giant red sea cucumbers live in the Pacific Ocean, ranging from the southern coast of Alaska to Baja California. They inhabit depths from the intertidal zone to up to 820 ft (250 m), preferring rocky and sandy ocean floors.

Snake sea cucumber (Synapta maculata)

Snake sea cucumbers are the longest sea cucumbers in the world, growing to even 10 ft (3 m) in length. Their body is long and slender and, as the name suggests, resemble a snake. In general, sea cucumbers move by using their tiny tube feet underside their body. However, Synaptas move in undulating, wavelike motions due to their body length.

The color of snake sea cucumbers varies a lot, ranging from yellowish to brown color with wide stripes and patches of darker color. These sea cucumbers are also sediment feeders and use their tentacles to sift through the sand, looking for particles and capturing them directly.

Where they live: Snake sea cucumbers live in shallow waters of the Indo-Pacific Ocean on reefs and sany bottoms. They also live on the seabed among seagrasses and seaweeds, inhabiting depths to about 66 ft (20 m).

Tiger’s tail sea cucumber (Holothuria thomasi)

Tiger’s tail sea cucumber is the largest sea cucumber species in the western Atlantic Ocean and can grow to about 6.6 ft (2 m) long. The name of this species comes from their characteristic elongated cylinder with rounded ends and a body covered with white stripes.

The body of tiger’s tail sea cucumbers is dark-golden brown in colors, covered with white patches and streaks. On the upper side, there are thorn-like projections (papillae) which are dark brown and tipped with white.

Interestingly, this sea cucumber is so good with camouflage that it was first described in 1980.

Where they live: Tiger’s tail sea cucumbers live in the Caribbean Sea, the Gulf of Mexico, and other surrounding areas. They inhabit coral reefs at depths from 9.8 ft (3 m) to 98 ft (30 m).

The smallest sea cucumbers

Thyonina bijui

Thyonina bijui sea cucumbers are one of the smallest sea cucumbers recorded and can grow to a size of just 0.8 in (2 cm). This species was found was identified as a new species by Professor Ahmed Thandar while describing several species of sea cucumbers from the Indian Ocean.

These sea cucumbers have a barrel-shaped body and are reddish brown in color. On their dorsal surface, they have plenty of tube feet that help them with locomotion and food capture.

Where they live: We don’t know too much about this species yet, but they were found in Indian Ocean.

Other species

While they’re probably plenty of tiny sea cucumber species, we haven’t identified them yet. Because of their size, it’s much more difficult to discover the smallest species. It is worth knowing that the larvae of sea cucumbers are very small, reaching only around 1 mm (39 mils) in length.

The juvenile sea cucumbers – which are the fourth stage of the sea cucumber life cycle – reach lengths between 0.5 mm (0.02 in) and 1.5 mm (0.06 in) and grow to the adult stage for a few years.

How much do sea cucumbers weigh?

Sea cucumber weight can vary a lot depending on the species and their body. For instance, one of the largest sea cucumbers is the snake sea cucumber, but its body is very thin and long, so it’s not the heaviest species.

The giant red sea cucumber is very massive and round and can weigh about 2.2 Lb (1 kg). Interestingly, not only the body posture influences the weight of sea cucumbers, but their internal organs and the coelomic fluid and water inside of their body that is used for breathing and circulatory system.


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