How do killer whales reproduce

While calves may start experimenting with solid food at a young age, they likely do not fully wean until around the age of 3. The Southern Resident killer whales have unusually low reproductive output, lower even than their nearby neighbors, the Northern Residents. Of the whales that have been assigned an ID by the Centre for Whale Research since , about 1 in 6 died before their first birthday. Given the high rate of pregnancy failure and the low survival of calves, the story is grim: any given pregnancy has about a 1 in 5 chance of resulting in a calf that survives for more than a year.

What is driving this low reproductive output? Analyses of demography and hormones point towards reduced prey availability. Controlling for age, females are more likely to reproduce in years following years of high Chinook salmon abundance, and spontaneous abortions are correlated with hormonal evidence of nutritional stress.

The survival of calves and all Southern Residents is also correlated with salmon abundance. Additional stress comes from persistent organic pollutants, such as polychlorinated biphenyls PCBs.

These toxins get passed from the mother to the calf during gestation and nursing, which could cause pregnancies to fail and young calves to die. Killer whales as a species are already slow to reproduce, with their long interbirth interval, old age of first reproduction, and long post-reproductive lifespan.

To get the Southern Resident population growing, it is imperative that they are allowed to have an adequate food supply, which means increasing the abundance of Chinook salmon in our waters. Bigg, M. Phantom Press, Nanaimo, BC.

In most births, the tail goes outside first, but there are also cases registered where the head is the first body part that has been exposed. As most mammal mothers, females tend to protect their young against other predators and remain beside them until they are capable of protecting themselves.

During this period, they learn to hunt and defend. Males do not have any parental contact with the young. According to a water park located in the United States, newborns have a length of 2. Their dorsal fin and tail are flexible during this period of immaturity, but as they grow both will strengthen to acquire a rigid texture. Younger orcas maintain a yellow tone in the skin that turns white as they grow, but as we can sometimes see, yellow tones fail to disappear from some adults.

Clicks seem to be used only for echolocation. Killer whales do have good vision, but in dark water their vision is not helpful in catching prey or navigating. As in other toothed whales , killer whales use sonar to perceive their aquatic environment. The whale's ears are very small openings behind the eyes, which have no outer flap.

The killer whale hears the whistles and clicks through an auditory bulla earbone complex in its lower jaw. The sound waves enter through the jaw where they then enter into the earbone complex. In this auditory bulla, there are bones that are like the bones found in the human ear. They waves travel trough these bones, then enter into the brain via an auditory nerve.

Bower, ; Deeke, et al. Killer whales are exceptionally successful predators. Orcinus orca diet is difficult to study and is most frequently assessed through looking at stomach contents. They eat a wide variety of large prey including: seals , sea lions , smaller whales and dolphins , fish , sharks , squid , octopi , sea turtles , sea birds, sea otters , river otters , and other animals.

Killer whales eat on average 45 kg of food a day, but they can eat much more than that. They swallow small prey whole, but tend to tear up larger prey before consumption. Killer whales are social hunters, as are wolves and lions. They often hunt in packs and use coordinated social behavior and communication to hunt prey larger than themselves, such as larger whales. Heintzelman, ; Mann, et al. Killer whales have no natural predators, although young killer whales may be attacked by other killer whales or large sharks.

They are at the top of the marine food chain. Humans sometimes prey on killer whales, but not in great numbers. Killer whales are top predators in most marine ecosystems and impact the populations of common prey, such as seals and sea lions in breeding areas.

Killer whales are host to some endoparasites and ectoparasites. They are host to killer whale lice Cyamus orcini , trematodes Fasciola skiranini , cestodes Trigonocotyle spasskyi , and nematodes Anasakis simplex.

A disease that affects killer whales and is often studied is toxoplasmosis Toxoplasma gondii. While this parasite is often benign, it can have serious and fatal effects. Chadwick, ; Murata, et al.

Killer whales are hunted and used for a number of things. In various parts of the world, they are used for oil and meat. Meat is sold for human consumption or used for fertilizer or bait. There are no known adverse effects of Orcinus orca on humans.

According to the IUCN red list there is insufficient data about killer whale populations to assess their status. The data on the endangered species act list states that killer whales are endangered.

They are on Appendix II of the CITES site, which means they are not threatened by extinction, but conservation efforts must be employed to help keep them from moving closer to extinction.

Killer whales have not been as directly impacted by human exploitation as other whale species. They are occasionally hunted but management of harvests seems to have been effective. The fossil history of killer whales dates to the Pliocene epoch, about 5 million years ago. The fossil history is not rich, but some finds link Orcinus orca to its early ancestors. Teeth, partial skulls, jaw bones, and periotic bones found in a mammal's ear have been found and identified in many countries of the world, including: Japan, Hungary, Italy, and South Africa.

Heyning and Dahlheim, It is the second largest ocean in the world after the Pacific Ocean. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.

Synapomorphy of the Bilateria. Found on all continents except maybe Antarctica and in all biogeographic provinces; or in all the major oceans Atlantic, Indian, and Pacific. The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a now extinct synapsid ancestor; the fossil record does not distinguish these possibilities.

Convergent in birds. Iteroparous animals must, by definition, survive over multiple seasons or periodic condition changes. An aquatic biome consisting of the open ocean, far from land, does not include sea bottom benthic zone. Bower, B. Culture of the Sea. Science News , Vol. Chadwick, D. Evolution of Whales. National Geographic , Vol. Deeke, V. Ford, P. Estes, J. Tinker, T. Williams, D.

Science, New Series , Vol. Demaster, D. Doak, T.