A seal of Antarctic coasts. It swims beneath sea ice and breathes through holes and cracks in the ice.
The head is small relative to the body. Its back is mottled gray and black, with a mostly white underside.
In McMurdo Sound, Antarctica, an underwater observatory recorded Weddell seal calls. Researchers examined 13 months of recordings from November 2017 to November 2018 and found nine recurring call types containing elements with fundamental frequencies at or above the usual upper limit of human hearing, about 20 kHz. Some calls combined many brief sounds; one began at as high as 49.8 kHz. Eight of the nine types were detected in at least 11 of the 13 months.
Comparing one 24-hour recording in spring with one around the winter solstice, researchers found that two repeated high-pitched calls made up 62% of the ultrasonic calls recorded on the winter day. The role of these high calls remains unknown: they may help seals communicate with one another or provide clues about their surroundings beneath the ice. The Weddell seal's underwater voice reaches far beyond the range humans can hear.
IUCN Red List · Least Concern (LC) · Global
The 2026 global IUCN Red List assessment classifies the Weddell seal as Least Concern (LC).