The sea otter interacts with a variety of animals around it for a variety of reasons. In fact, the sea otter is recognized as a keystone species in the rocky sub tidal habitats (Costa, 2011). This means that the sea otter has a greater impact on its community than would be assumed based on its population. Although no animals were responsible for the demise of the sea otter, they all can impact how prosperous the sea otter is in its current environment. A few of these animals are the sea urchin, the Toxoplasma gondii, kelp, the great white shark and the bald eagle (Costa, 2011).
Sea Urchin
The sea urchin is a class of echinoderms, who live on the rocky bottom of ocean floors. They can live in either cold or warm water, but must live in salt water environments. These small creatures will be captured by sea otters when they dive, and brought to the surface. In this predator-prey relationship, where the urchin is the prey and main source of food for the sea otter, sea urchins play a large role in the population growth for the otter (Costa, 2011). If there was a decrease in sea urchin population, this would consequently have an adverse effect on the sea otter. Although, the sea otter is a very versatile consumer, it is possible that this could harm the sea otter population. However if there was an abundance of sea urchins, this would be very beneficial because food would not limit the sea otter’s population. This would encourage an increase in sea otter population, and possible expansion into other areas of the coastline.
Toxoplasma gondii
Another species that the otter interacts with is the parasite known as Toxoplasma gondii. These parasitic protozoans are a major cause of death within the sea otter community. In this parasitic relationship, the sea otter is harmed while the protozoan benefits (Costa, 2011). This relationship has a severely negative effect on the otter population. Although diseases and parasites are not generally a major cause of death for otters, this particular parasite is especially detrimental to southern coastal otter populations. For this reason, the sea otter population growth would be stunted by such a parasite, which has the ability to kill many individuals.
Brown Algae
The sea otter also has an ongoing relationship with brown algae (aka kelp) which is mutualistic (Costa, 2011). In this relationship, the sea otter eats sea urchins, as discussed above. These urchins would usually eat the majority of the kelp; however the sea otters can prevent this. Sea otter benefit from this relationship because they use kelp to anchor themselves when they sleep. Although this relationship does not have a direct impact on the sea otter population growth patterns, it is beneficial.
Great White Shark
The great white shark is one of the most feared predators all over the world. This shark lives along coastlines and around the equator because of the warm water temperatures. The great white will prey on the sea otter as a source of food along the north eastern coast of the Pacific Ocean. In this predator-prey relationship, the sea otter is the prey, and its population is directly impacted by the shark (Costa, 2011). If there is a larger population of sharks in the area, the population of sea otter will be greatly affected. This could repress population growth in an area with many sharks within the territory.
Bald Eagle
Finally, the bald eagle is known to prey on sea otter pups. This is important because the pups are those who would be reproducing in the future. Because the bald eagles prey on the pups specifically (because of their size) this can change the age structure of the sea otter population. In this predator-prey relationship, the sea otter pups are the prey, and the bald eagle is the predator (Costa, 2011). This could have a detrimental effect on the sea otter population, because removing a large portion of the pups from the population would have adverse effects on the population many years into the future.