Antarctic walrus (SciiFii)

The Antarctic walrus (Odobedelphis antarctica) is a species of toothed whale, despite its name, and the only living member of the dolphin family Odobedelphidae that originally did not exist, but has since been created by SciiFii and introduced throughout the Antarctic Ocean to help boost biodiversity. The Antarctic walrus is a rather large dolphin species, with males growing up to 5.5 meters (18 feet) long and weighing up to 1,600 kilograms (3,530 lbs). This whale has a stocky body and, like many cetaceans, a large percentage of its weight is blubber (subcutaneous fat). Its sense of hearing is highly developed and its echolocation allows it to move about and find breathing holes under ice sheets. The Antarctic walrus has a diverse and opportunistic diet, feeding on more than 60 genera of marine organisms, including shrimp, crabs, tube worms, soft corals, tunicates, sea cucumbers, various mollusks, and even parts of other pinnipeds. However, it prefers benthic bivalve mollusks, especially clams, for which it forages by grazing along the sea bottom, searching and identifying prey with its echolocation and clearing the murky bottoms with jets of water and active fin movements. The walrus sucks the meat out by sealing its powerful lips to the organism and withdrawing its piston-like tongue rapidly into its mouth, creating a vacuum. The walrus palate is uniquely vaulted, enabling effective suction. The diet of the Antarctic walrus consist almost exclusively of benthic invertebrates (97 percent). Aside from the large numbers of organisms actually consumed by the Antarctic walrus, its foraging has a large peripheral impact on benthic communities. It disturbs (bioturbates) the sea floor, releasing nutrients into the water column, encouraging mixing and movement of many organisms and increasing the patchiness of the benthos. Antarctic walruses live to about 20–30 years old in the wild, but can live more than 50 years in captivity. The males reach sexual maturity as early as seven years, but do not typically mate until fully developed at around 15 years of age. They rut from August through November, decreasing their food intake dramatically. The females begin ovulating as soon as four to six years old. The females are diestrous, coming into heat in late winter and also around September, yet the males are fertile only around September; the potential fertility of this second period is unknown. Breeding occurs from August to October, peaking in September. Males aggregate in the water around ice-bound groups of estrous females and engage in competitive vocal displays. The females join them and copulate. Gestation lasts 15 to 16 months. The first three to four months are spent with the blastula in suspended development before it implants itself in the uterus. This strategy of delayed implantation, common among whales, adapted to optimize both the mating season and the birthing season, determined by ecological conditions that promote newborn survival. Calves are born during the summer, from November to March. They weigh 45 to 75 kg (99 to 165 lb) at birth and are able to swim. The mothers nurse for over a year before weaning, but the young can spend up to five years with the mothers. Antarctic walrus milk contains higher amounts of fats and protein compared to land animals but lower compared to many cetaceans. This lower fat content in turn causes a slower growth rate among calves and a longer nursing investment for their mothers. Because ovulation is suppressed until the calf is weaned, females give birth at most every two years, leaving the Antarctic walrus with the lowest reproductive rate of the majority of the whales. The conservation status of the Antarctic walrus is Least Concern due to successful conservation efforts and the Antarctic walrus's wide range.