habitat_narrative
Marine
With the exception of the Black Sea and probably the Red Sea, Sperm Whales occur within all major marine water bodies deeper than 1,000 m that are not covered by ice sheets (Rice 1989; Whitehead 2003). They are predominantly located in deeper waters of the open sea. However, they (especially males) may occasionally frequent shallower waters of the western North Atlantic (Scott & Sadove 1997). Females and young are most commonly limited to waters exhibiting sea surface temperatures greater than 15 °C (Rice 1989); and at latitudes lower than 40°N and 40°S. Their abundance and habitat selection usually increases with primary productivity (Jaquet et al. 1996; Rendell et al. 2004).Sperm Whales are sexually dimorphic. Males may reach lengths of up to 18.3 m, while mature females may have a mass three times less than that of mature males, reaching lengths of 12.5 m. A 13.3 m male Sperm Whale weighed on a railway loading truck in Durban was 31,450 kg (Gambell 1970), but the heaviest recorded Sperm Whales included a male of 18.1 m at 57,000 kg and a female of 11.0 m at 24,000 kg. Sperm Whales have a substantial ecological footprint, and may consume roughly the same amount of biomass of marine resources as humans (Whitehead 2003).
Mesopelagic squid form the principal food source for Sperm Whales; however, in certain regions bottomdwelling fish are also commonly taken (Roe 1969). In South African waters, squids with an average weight of 0.5â 0.6 kg are usually consumed, while in the Antarctic, much larger squid (about 7.0 kg) are commonly preyed upon. The largest recorded squid found in the belly of a Sperm Whale was a Giant Squid (Architeuthis spp.) weighing 184 kg and 4.94 m long. Additional Sperm Whale foodsources documented off the west coast of South Africa include crabs and tunicates (most commonly eaten by males), mysids and oilfish (more frequently eaten by females), and rays, angler fish and lancet fish (only eaten by males) (Best 1999). Adult males and females are thought to consume approximately 2% and 3% of their body mass per day, respectively. Bottom-dwelling sharks found in the stomach of a Sperm Whale collected in Durban suggest that the whale would have dived over 3,000 m deep.
The breeding season of Sperm Whales in the southern hemisphere peaks between October and December. Females usually produce calves every three or five years; however, this duration increases with age (Rice 1989). Following a gestation period of 15â16 months, one calf (about 4 m in length) is born. Solid food is consumed before the calf reaches a year old; however, the stomachs of some individuals still contained evidence of milk at ages of 7.5 years and 13 years for females and males, respectively. Sexual maturity is reached at an age of 7â13 years (lengths of 8.5 m) for females, and at around 20 years (lengths of 12.5 m) for males; however, males only reach the status of a âbreeding bullâ once they are around 25 years old (lengths of 13.7 m).
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; migratory mysticete whales may be used to investigate broad-scale shifts in ecosystems (Moore 2008). Sperm Whales are also important reservoirs of, and vectors for, nutrients (Roman et al. 2014), thus influencing oceanic ecosystem functioning. A Sperm Whale is the main antagonist (or protagonist, depending on your point of view) in the classic novel Moby Dick by Herman Melville.
