07-05-2025
Sea pigs, icefish and trilobites: Antarctica's mysterious marine life
Southern fulmars flock around a swell of pancake ice off the coast of the Denman Glacier in East Antarctica.
True trilobites went extinct more than 250m years ago, but the Southern Ocean is home to a living lookalike: Ceratoserolis trilobitoides . They have a segmented, armoured exoskeleton, which helps protect them from predators.
The Victoria brittle star has five slender arms that can span up to 10cm. It is both a predator and a scavenger, feeding on an array of invertebrates (including krill), organic detritus and even juvenile brittle stars. This species can regenerate lost limbs much faster than other echinoderms.
These amphipods are small shrimp-like crustaceans found on Antarctica's seafloor. They are carnivores, feeding on polychaetes, amphipods, small crustaceans and other organic detritus.
This scale worm has been photographed from the underside. It is one of the more bizarre-looking creatures living on the ocean floor, known for its flat body covered in ornamented scales called elytra. This particular large Antarctic scale worm is adorned in an iridescent gold 'coat', making it one of the more glamorous creatures on the seafloor. Less glamorous are its eating habits: carnivorous, its retractable proboscis projects itself during feeding, making the worm look like it has massive jaws with fangs.
The Sea pig gets its name from its pink-hued body and love of the muddy sea floor, but it's actually a type of sea cucumber. It uses its tube-like feet to move across the sea floor, scavenging for bits of nutrient rich organic food – nature's vacuum cleaner!
The ship is now sailing home from its first scientific voyage. It spent about two months off the coast of the Denman Glacier, one of the fastest retreating glaciers in East Antarctica.
This isopod is a slow-maturing species that breeds only once in its lifetime. Females brood eggs in a marsupium, or pouch, where young develop for nearly two years before emerging as juveniles.
Jonah's icefish is notable for its adaptation to the extreme cold. Unlike most vertebrates, it lacks haemoglobin, resulting in nearly transparent blood. It relies on dissolved oxygen in its plasma to transport oxygen through its body, which allows it to thrive in the cold, oxygen-rich waters of the Southern Ocean.
A team from Securing Antarctica's Environmental Future, led by James Cook University's Prof Jan Strugnell, is trying to answer two questions: what is the diversity, distribution and connectivity of marine invertebrates in East Antarctica? And what is the history of the ice in the region?
The spikes on this scale worm stick out from bristle-bearing appendages that it 'walks' on. The spikes are modified hard bristles called chaetae.
Pareledone is a genus of octopus found only in Antarctic waters. These seafloor dwellers live in shallow water and as deep as 4,000 metres. One Pareledone, the Turquet's octopus, helped scientists understand a mystery that had long puzzled them. Genetic analysis found that distinct populations from the Weddell, Amundsen and Ross seas interbred 125,000 years ago, showing that the West Antarctic ice sheet melted during the last interglacial, a time with climate conditions much like today.
With more than 500 described species, Nereidid worms are one of the most widespread polychaete families. They have been found living in a wide range of marine habitats. This Nereidid worm beautifully displays the characteristic chaetae-bearing lateral body segments called chaetigers.
Antarctic sea spiders can grow to unusually large sizes — a phenomenon called polar gigantism. Despite its name and appearance, it is not related to terrestrial spiders, with the fossil record suggesting that its evolution pre-dates land spiders by millions of years. The sea spider absorbs oxygen through its exoskeleton, essentially using its legs to breath! This one is about 20cm in diameter.
The team from Securing Antarctica's Environmental Future on the back deck of the RSV Nuyina.
