In freezing sea temperatures as low as -2°C, only the toughest creatures can survive in Antarctica’s brutal marine conditions. One particularly formidable species, however, is built to dominate these icy depths, though it bears little resemblance to its familiar five-armed relatives.
- In 1941, a massive WWII ship sank off the coast of Albania. Divers just went down there – and found a rare mammal living among the wreck
- “I screamed before the rest of it came into the screen.” Deep-sea scientists film rare creature deep in Pacific Ocean
The Antarctic sun starfish (Labidiaster annulatus), also known as the wolftrap starfish, is one of 2,000 known sea star species on Earth, yet it stands out as one of the most remarkable. Scientists exploring the Southern Ocean during BBC’s Blue Planet expedition dubbed it the "Death Star”.
Known collectively as ‘asteroids’, these spectacular echinoderms look positively otherworldly. Very little is known about this deep-sea predator, but what scientists have uncovered is remarkable.
How big are Antarctic sun seastars?
Sprawling up to 60 centimetres in diameter, this predator navigates the seabed at depths ranging from 30 to 500 metres. You’ll find it lingering among sand, gravel and rocks in search of its next meal.
How many arms do Antarctic sun seastars have?
While standard sea stars typically feature five arms (also known as rays), predatory species often possess far more. The Antarctic sun starfish is an extreme example, growing up to 50 slender, flexible rays that resemble octopus tentacles.
These rays are lined with raised, fleshy bands called annuli, which are densely covered in microscopic, jaw-like pincers known as pedicellariae. With up to 80 pedicellariae per band, its arms function like rows of snapping bear traps.
How do they catch their prey?
To hunt, the Antarctic sun starfish scales a tall rock or sponge to elevate itself. Anchoring firmly with a few of its limbs, it extends the rest like a network of flexible traps.
Once an unsuspecting animal makes contact, the pedicellariae clamp shut, locking the struggling prey in place. The sea star then uses its specialised tube feet to manoeuvre the catch directly into its central mouth.
What do Antarctic sun seastars eat?
An opportunistic hunter, the Antarctic sun starfish will target almost anything its size on the ocean floor. Analysis of stomach contents reveals a diet of krill, amphipods, small fish and even other sea stars.
In the dark, freezing realm of the Antarctic seafloor, the wolftrap starfish stands as a masterclass in evolutionary adaptation. It’s a specialised predator perfectly suited to thrive in one of the planet's most extreme environments.
Top image: Labidiaster annulatus taken during Waldo Schmitt's collecting during the Palmer Peninsula Survey 1962-1963. Credit: Smithsonian Institution Archives, No restrictions, via Wikimedia Commons
