Ross Seal, Ommatophoca rossii
The Ross seal (Ommatophoca rossii) is a true seal in the Phocidae family, and can only be found on pack ice in Antarctica. This species was formally described by James Clark Ross in 1841, during his British Antarctic Expedition. It is very uncommon to see in its range and rarely leaves the pack ice, with stray individuals occurring off southeast Australia or sub-Antarctic islands.
The Ross seal can reach an average length between 5.5 and 6.9 feet, although some females can reach up to 8.2 feet in length, with an average weight between 280 and 480 pounds. The dorsal fur of this species in warmer months is dark brown while the underbelly is whitish silver, but in colder months, the coat becomes light brown in color. Its large eyes, which can reach a diameter of 2.7 inches, help distinguish it from other seal species.
Typically, the Ross seal appears to be solitary, but it can occur in small groups, which are located far from other individuals. These seals communicate using a wide variety of vocalizations, which consist of twittering calls that can be made under water and on the ice, and can travel long distances. Whether the seals are calling underwater or on the ice, they keep their mouths closed to save air. It is thought that the purpose of these calls is to avoid encounters or initiate them, although more studies are needed to confirm this.
The breeding season of the Ross seal is thought to occur shortly after a pup is born in late November. Pups are born on the ice weighing approximately 35.6 pounds. Weaning occurs at one month of age, but sexual maturity is reached at three years of age. The average lifespan of this species in the wild is twenty years. Its diet consists of fish and cephalopods like squid. It is thought to be preyed upon by orcas and leopard seals, which share its range, although there are no records of this.
The total population of Ross seals is thought to range between 20,000 and 227,000, although it is widely accepted that the number is actually around 130,000 individuals. Because there is not much known about its habits and population numbers, it is not known whether the total population is stable or declining. It does not occur in areas near human settlements, so interactions with humans are rare. The Ross seal appears on the IUCN Red List with a conservation status of “Least Concern.”
Image Caption: A Ross Seal (Ommatophoca rossi). Credit: NOAA /Wikipedia