Fish
Bald Notothen
Pagothenia borchgrevinki · also called Borchgrevink's notothen
Living permanently pressed against the underside of Antarctic sea ice, a bald notothen tolerates direct contact with ice crystals that would kill most other fish, its blood packed with natural antifreeze proteins built for exactly this habitat.
Overview
The bald notothen, Pagothenia borchgrevinki, is a Least Concern fish native to ocean and polar habitat across coastal waters and sea-ice zones surrounding Antarctica. Its unique sea-ice-associated lifestyle, antifreeze-protected blood, and role as prey for seabirds and seals make it one of the more ecologically specialised fish species found anywhere in Antarctic waters.
A fish that lives against the ice itself
While most cold-adapted Antarctic fish avoid direct contact with ice, the bald notothen has instead built its entire life around living right against the underside of sea ice, tolerating conditions that would freeze almost any other fish solid.
Status
Least Concern, remaining present across suitable sea-ice habitat surrounding Antarctica, though its close dependence on sea ice makes it a subject of ongoing interest amid a changing Southern Ocean.
Bald Notothen: common questions
Where does the bald notothen live?
This species lives permanently in the layer of water directly beneath Antarctic sea ice, a habitat few other fish species are able to exploit successfully.
How does the bald notothen survive contact with ice?
This species produces natural antifreeze glycoproteins that circulate in its blood, preventing ice crystals from forming even in direct contact with sea ice, and can tolerate small ice crystals on its skin without harm.
Why does the bald notothen have such a slender body?
This species has an unusually slender, elongated body compared with many related Antarctic fish, an adaptation suited to manoeuvring within narrow channels in the sea ice.
Why is the bald notothen ecologically important?
This species serves as an important prey item for seabirds and seals that forage near the underside of sea ice, forming a key link in the Antarctic coastal food web.