Kogia simus

Dwarf Sperm Whale

Family: Kogiidae · Class: Mammalia · Order: Artiodactyla

The dwarf sperm whale is a small cetacean measuring 2.1 to 2.7 meters (6.9 to 8.9 feet) in length and weighing 136 to 272 kilograms (300 to 600 pounds). The species exhibits sexual dimorphism, with females typically larger than males. The body is robust and shark-like in profile, with a distinctive underslung lower jaw that does not extend beyond the tip of the upper jaw. The dorsal coloration is dark gray to blue-gray, fading to lighter gray or white on the ventral surface. A pale bracket-shaped mark extends from behind the eye toward the flipper, resembling a gill slit. The dorsal fin is small, falcate, and positioned in the posterior third of the body. The head is squarish in profile with a narrow rostrum, and the blowhole is positioned slightly left of center on top of the head. Dwarf sperm whales occur in deep oceanic waters worldwide between approximately 40°N and 40°S latitude. Along the California coast, the species inhabits waters beyond the continental shelf, typically in depths exceeding 200 meters (656 feet). Strandings have been documented from Humboldt County to San Diego County, with most records from central and southern California. The species appears to be year-round residents in California waters, though seasonal movements may occur in response to prey availability. The species occupies pelagic and mesopelagic zones of the open ocean, preferring waters with steep bottom topography such as continental slopes and submarine canyons. Dwarf sperm whales are typically found in water temperatures ranging from 10 to 25°C (50 to 77°F). They demonstrate a preference for areas with high squid abundance, often associated with upwelling zones and areas of enhanced productivity. Dwarf sperm whales are deep-diving specialists, capable of reaching depths of 300 meters (984 feet) or more during foraging dives. Their diet consists primarily of cephalopods, particularly squid species in the families Cranchiidae, Onychoteuthiidae, and Histioteuthiidae. Fish, shrimp, and other crustaceans constitute secondary prey items. The species employs suction feeding, using their protrusible tongue to capture prey. Breeding appears to occur year-round, with a gestation period of approximately 9 to 11 months. Females give birth to a single calf measuring about 1 meter (3.3 feet) in length. Sexual maturity is reached at 2.1 to 2.2 meters (6.9 to 7.2 feet) in length. When threatened, dwarf sperm whales release a reddish-brown intestinal fluid, creating a defensive cloud similar to squid ink. The dwarf sperm whale is not federally listed under the Endangered Species Act and lacks specific state protection status in California beyond general marine mammal protections. Population estimates are uncertain due to the species' offshore distribution and cryptic behavior. Primary threats include entanglement in fishing gear, ship strikes, noise pollution, and marine debris ingestion. Climate change may affect prey distribution and ocean temperature patterns. The species falls under the Marine Mammal Protection Act, which prohibits harassment, capture, or killing of marine mammals in U.S. waters.

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, and more.