Despite its name, the crabeater seal feeds mainly on krill, small, shrimp-like crustaceans. Their specialized teeth are used to strain prey as the seal gulps seawater. They forage primarily at night, resting on ice floes during the day. Crabeater seals are unique among the phocid seals in that they form “family” groups consisting of an adult female, her pup, and an adult male. Females give birth to a single pup. A male usually joins a pregnant female shortly before or after the pup's birth. He remains with the female on the ice until after the pup is weaned, at which time mating occurs. The seals breed on the ice from early October to mid-November. During the time a family group is together, the adult male defends the female and pup from other adult males and predators.
Male crabeater seals are especially vocal during the breeding season, producing two types of calls, the groan-like “low moan” call, and the “high moan” call. The low moan lasts about 2.5 s with a frequency range of 260-2500 Hz. It rises to a constant frequency and decreases at the end. The high moan call is characterized by a brief down sweep followed by a series of short pulses. This call lasts about 2.6 s with a frequency range of 1000-4900 Hz.
As males remain with females and their pups during the breeding season, it is thought that they do not need to vocalize to attract a mate. However, they may need to communicate their status, and possibly compete, with rival males. Crabeater seals appear to respond to distant groans with their own low moans.Crabeater seals have been found to produce sounds outside the breeding season. These sounds include groans, whistles, screeches, and grunts. The function of these sounds remains unknown.
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- "Crabeater Seal." In: Encyclopedia of Marine Mammals (Second Edition). Editors: William F. Perrin, Brend Wursig, J.G.M. Academic Press. Amsterdam. 2009. Pp 290-29.
- Australian Antarctic Division, "Crabeater Seals." (Link)
- Klinck, H., D.K. Mellinger, K. Klinck, and J. Hager 2010, "Long-range underwater vocalizations of the crabeater seal (Lobodon carcinophaga)" Journal of the Acoustical Society of America. 128(1): 474-479.
- McCreery, L. and J.A. Thomas. 2009, "Acoustic analysis of underwater vocalizations from crabeater seals (Lobodon carcinophagus): Not so monotonous." Aquatic Mammals. 35(4): 490-501.
- National Marine Mammal Laboratory, "Crabeater Seals." (Link)
- NOAA Fisheries Service, "Crabeater seal fact sheet." (Link)
- Sea World Animal Bytes, "Crabeater Seal." (Link)
- Van Opzeeland, I., S. Van Parijs, H. Bornemann, S. Frickenhaus, L. Kindermann, H. Klinck, J. Plotz, and O. Boebel. 2010, "Acoustic ecology of Antarctic pinnipeds." Marine Ecology Progress Series. 414: 267-291.