About the classification of the Sea Otter:

1. Domain: Eukaryote 

Explanation: The otter is a Eukaryote for it contains all traditional cell parts and those are highly organized to perform very specialized tasks. [68]

Eukaryotes contain an organized, membrane-bound nucleus and organelles. The nucleus contains DNA and essentially directs the cell on what actions it shall perform. [68] Therefore, the otter is composed of millions of Eukaryotic cells, hence it is a eukaryote!

2. Kingdom: Animalia

Explanation: This kingdom only possesses multicellular members, or eukaryotes. They are heterotrophs, as they depend on other organisms directly or indirectly for food. Otters are unable to perform photosynthesis, hence are consumers - they are heterotrophs. Most of the animals ingest food and digest in the internal cavity, and most organisms are motile, with the ability to move independently and spontaneously, reacting to stimuli. [42] Otters react to stimuli, are able to move freely and idenpendently and for this reason are in the kingdom Animalia. 

3. Phylum: Chordata

Explanation: A common characteristic among chordates is the presence of a dorsal nerve cord, or bundle of nerve fibers that runs down the top of the animal, connecting it to the brain with the muscles and other organs. [25] Otters possess this, and have a backbone for the entirety of their life - they are vertebrates. Another characteristic present in members of the Chordata Phylum is a notochord, rod running underneath the skin which supports the nerve cord. [25] Lastly, otters possess post-anal tail. This is an extension of the body past the anal opening - in fact, otters possess a long tail. [25] 

4. Class: Mammalia

Explanation: Though the diversity between mammals in huge, there are three characteristics shared between mammals. The first characteristic is the possession of 3 middle ear bones: malleus, incus, and stapes (hammer, anvil, and stirrup), which transmit vibrations from the tympanic membrane (eardrum) to the inner ear.

The second characteristic is Mammalian hair, present in all mammals at some point in their development. These serve for insulation, color patterning, and aiding in the sense of touch. Lastly, all female mammals produce milk from their mammary glands in order to nourish newborn offspring. [5] Because otters are warm blooded, possess a hammer, avil and stirrup, are covered in mammalian hair and females produce milk for their offspring, sea otters are mammals.

5. Order: Carnivora

The word "Carnivora" literally means "flesh devouring" in Latin. Therefore, as can be inferred through this translation, carnivores are organisms that get most of their food by killing and eating other animals, including other mammals, birds, insects, and fish. [70] Since the sea otter's diet consists of meat, notably sea urchins, mussels, clams, crabs and other marine animals, they are carnivorous.

6. Family: Mustelidae

This is the family of weasels, otters and badgers. These possess elongate bodies with short legs and a short rostrum - sea otters clearly have those characteristics. Mustelids have a powerful bite, as they lock the lower jaw into the upper, causing the lower jaw to only move in the vertical plane, without any rotary motion. [71] Otters possess all these characteristics and are therefore classified in this family. 

7. Genus: Enhydra 

Sea otters are the only member of the Genus Enhydra, and therefore, the characteristics of this genus all pertain to the sea otter. [72]

8. Species: Lutris

Species lutris only specifies that the species that is being mentioned is the Enhydra lutris instead of another sort of Enhydra. For example, there are Because there is only one kind of lutris and that is the Enhydra lutris, sea otters have now been classified! [6]