Last updated on February 5th, 2022
Sea urchins belong to the Echinoidea class and are globular, spiny echinoderms. Their 3-7 m diametrically long shells are spiny, round, and hard.
Animals that eat sea urchins:
- Sea otter
- Parrot fish
- Moray eel
Sea urchins predominantly feed on algae, and thus, they are majorly herbivores, but they may also include slow-moving animals in their diet.
They may eat sea cucumbers along with various invertebrates like crinoids, brittle stars, polychaetes, and mussels.
They also move slowly by crawling with their tube feet, and with the use of their spines, they propel themself.
Approximately 950 of its species live on every depth zone and ocean’s seabed. Numerous species feed on sea urchins in the food chain, excluding human beings. Here we bring you some animals that include it in their diet.
Here are 7 animals that eat sea urchins
1. Sea Otters
These marine mammals are indigenous to the northern and eastern sides of the North Pacific Ocean’s coasts.
No other weasel family member is as heavy as sea otters; the full-grown ones usually weigh around 14-45 kg and they can walk on land and live solely in the oceans.
Their main means of insulation is their fur that’s remarkably thick. Previously, they were estimated to be 150,000-300,000 of these creatures, however, they were heavily hunted during 1741-1911 for their fur, and their number fell to 1,000-2,000.
Their habitats are in nearshore environments and they predominantly prey on a few fish species, numerous crustaceans, and mollusks, as well as sea urchins.
They use rock as a tool to open their prey’s shell and even to dislodge it.
They restrain the sea urchin population that would have imposed substantial damage to the kelp forest ecosystems, making them keystone species.
2. Parrot Fishes
Parrotsfishes are seen in seagrass beds, rocky coasts, and coral reefs; the Indo-Pacific possesses the group’s highest species richness.
Their group consists of approx 90-95 species and plays a notable part in bioerosion. Their sizes vary according to their species, although most of them attain the length of 30-50 cm.
Some species can even exceed the length of 1 meter; they are generally herbivores and mostly feed on epilithic algae.
A few times, they include little organisms like detritus, bacteria, and invertebrates in their diet.
Some of its largest species, like the green humphead parrotfish, majorly feed on polyps and living corals.
They aren’t exclusively corallivores, but almost half of their diet or even more can consist of polyps.
Excluding the green humphead parrotfish, all of them incline more towards algae-covered surfaces than live corals. They may also be spotted eating sea urchins.
Starfish are also called Asteroids for they belong to the Asteroids class; these star-shaped echinoderms usually have a disc at the center with five arms, although the number of arms may vary across its distinct species.
Their life cycles are complex and they are capable of reproducing both asexually and sexually. They are capable of regenerating their lost arms or damaged parts.
Most of them are generalist predators that eat small animals, including snails, bivalves, sponges, and microalgae.
The rest are detritivores that depend on decomposing animal and plant matter as well as feces for their nutrition.
They also feed on sea urchins by wrapping themself around them.
Octopuses belong to the Octopoda order, and these are eight-limbed and soft-bodied mollusks.
Their habitat includes numerous regions in the oceans, consisting of oceanic waters, seabed, and coral reefs.
These are typically short-living creatures who grow quickly and mature early. Full-grown generally weighs between 14-16 kg, and their arm span can reach up to 14 ft.
They typically avoid humans, but several interactions have been confirmed; they are vicious creatures, although only the venom of the blue-ringed octopuses can be fatal to humans.
Younger ones usually feed on sea stars, larval crabs, and copepods, whereas the full-grown ones tend towards small fishes, snails, crabs, clams, and other octopuses.
Octopuses are rarely seen eating sea urchins, however, when other food sources are unavailable, they will consume what they can find.
Crabs belong to the order Brachyura and usually have a very small-sized projectile tail. They reside both on land and freshwater and are all found across all oceans globally.
They vary in size, however, the pea crab is a little millimeters wide, whereas the Japanese spider crabs can have a leg span of 4m.
Male crabs are aggressive against each other and often indulge in the fight to impress the opposite sex.
They are omnivores, and small crabs eat shrimp, small clams, worms, seaweed, and algae, whereas the larger ones feed on small fish, snails, squid, mussels, and even other crabs.
Additionally, crabs are one of the natural predators of sea urchins.
Pufferfishes are mostly toxic, and few of them are on the list of the world’s most poisonous vertebrates.
In some of its species, the liver and skin consist of tetrodotoxin, and it’s very toxic when eaten by most animals.
However, its meat is seen as a delicacy in China, Korea, and Japan. They are generally small-medium in size; some of its species can surpass the length of 50 cm, though.
They aren’t found in cold water, but they are very diverse in the tropics and comparatively rare in temperate zones.
Their typical diet primarily consists of algae and invertebrates. Large ones can even have shellfish, mussels, and clams. If they come across a sea urchin, then they will happily eat it.
7. Moray Eels
Moray eels are an eel family present across the globe; 15 genera roughly consist of 200 predominantly marine species.
A number of these creatures can be spotted in brackish water, while some are in freshwater. Their body is usually patterned, and the inner part of their mouth is also patterned in a few species.
Moray eels are carnivores and these opportunistic predators majorly feed on smaller octopuses, fish, and crabs. Once a red lionfish was observed to be eaten by a spotted moray eel.
Giant morays have been observed to be recruited by reef-associated roving coral groupers to hunt. They also feed on squid, cuttlefish, and sea urchins.
The animals that eat sea urchins are sea otters, parrotfishes, starfishes, octopuses, crabs, pufferfishes, and moray eels. Since sea urchins crawl with tube feet, it causes them to move slowly which makes them an easy target for these predators.