habitat_narrative
Marine
Pygmy Sperm Whales inhabit deep waters over the continental shelf and slope (Ross 1979; S. Plön pers. comm.). Although some studies document some division between K. breviceps and K. sima in their preference for water depth, Mullin et al. (1994) using aerial observations noted that in the Gulf of Mexico, both species occurred in waters between 400â600 m deep. These depths constituted the upper regions of the continental slope, which exhibited high concentrations of zooplankton (Baumgartner et al. 2001). Both species appear to feed over the deeper continental shelf and slope (Ross 1979; S. Plön pers. obs.).Ross (1979) reported that Pygmy Sperm Whales may occur individually or in small groups of up to six, whereas Dwarf Sperm Whales occur in socially-structured schools of up to ten individuals. Although they are capable of rapid bursts in speed, Pygmy Sperm Whales typically swim at about 5.5 km / h (Mörzer Bruyns 1971). While not commonly sighted at sea, Katona et al. (1983) reported that K. breviceps are easy to approach, as they often float on the surface of the water with much of their body exposed, contrasting with the Dwarf Sperm Whales, which lie very low in the water (Leatherwood & Reeves 1983).
The stomach contents of stranded Pygmy Whales contained the remains of deep-water cephalopods, suggesting that this species feeds at depths of up to 900 m (S. Plön pers. obs.). Similarly, the stomach contents of Dwarf Pygmy Whales insinuate that this species routinely dives to about 600 m to feed, possibly even deeper, and is mostly found over the continental shelf (Ross 1979; S. Plön pers. obs.). The majority of the diet of Kogia spp. consists of cephalopods, but they may also consume other prey, for example deep-sea fishes and shrimps (McAlpine et al. 1997; dos Santos & Haimovici 2001; S. Plön pers. comm.). Ross (1979) documented that in South African waters, Pygmy and Dwarf Sperm Whales consumed at least 67 and 38 different prey species, respectively, and Pygmy Sperm Whales are likely to feed in deeper waters compared to Dwarf Sperm Whales.
Although little is known about the reproductive biology of Kogia spp., and no seasonality can be inferred, female and male K. breviceps from South Africa are estimated to reach sexual maturity at 2.7â2.8 m and 2.7â3.0 m, respectively, while both sexes of K. sima reach sexual maturity at 2.1â2.2 m (Ross 1984). Pygmy Sperm Whale calves are born at an approximate length of 1.2 m and, surprisingly, an extremely high proportion (80%) of calves and foetuses were found to be male (Ross 1979).
Ecosystem and cultural services: Marine mammals integrate and reflect ecological variation across large spatial and long temporal scales, and therefore they are prime sentinels of marine ecosystem change (Moore 2008).
