Issue date March 27, 2018:
From Australia Post’s Stamp Bulletin:

This stamp issue focuses on the Crabeater Seal (Lobodon carcinophaga), which is thought to be the most numerous of the six seal species found in Antarctica. It has a circumpolar distribution and is largely restricted to the pack-ice zone of Antarctica, which uctuates in area as the pack-ice expands and contracts with the seasons. While it has been observed congregating in large groups, the Crabeater Seal is more commonly observed in groups of around three or as a solitary animal, partly the result of it occupying oating pack-ice, which can break into smaller floes.

The four stamps in this issue illustrate some aspects and behaviours of the Crabeater Seal: the female gives birth to a single pup each spring, which it raises alone; the species is generally a solitary animal or congregates in small groups; and while it is ungainly on ice, the Crabeater has great skill in the water. It can dive to around 600 metres and for periods of about 25 minutes.