Chordata · chordates

Sea otter

Enhydra lutris

Mustelidae · weasels & ottersIUCN: Endangered
Sea otter
Photo: Marshal Hedin from San Diego · CC BY-SA 2.0 · Wikimedia Commons · resized

The densest-furred mammal and a keystone predator of kelp forests.

Fun factIt floats on its back and uses rocks to crack open shellfish.

Waters
North Pacific, Eastern Pacific
Depth zone
Coastal shallows & estuaries
Diet
Urchins, clams & crabs
Size
Up to 1.5 m

Classification

Chordata › Mammalia › Carnivora › Mustelidae

  1. Kingdom Animalia animals
    • Many-celled organisms that eat other living things for energy (heterotrophs)
    • Cells have no cell walls
    • Most can move at some stage of life
  2. Clade Bilateria bilateral animals
    • Body has a left and right side that mirror each other (bilateral symmetry)
    • Head end with concentrated nerves; three tissue layers
    • Includes about 99% of all living animal species
  3. Clade Deuterostomia deuterostomes
    • In the embryo, the first opening becomes the anus and the mouth forms second
    • Includes echinoderms and chordates
  4. Phylum Chordata chordates
    • At some stage of life: a stiffening rod along the back (notochord)
    • A hollow nerve cord along the back (dorsal)
    • Slits in the throat (pharyngeal slits) and a tail past the anus
  5. Subphylum Vertebrata vertebrates
    • A skull (cranium) protecting a brain
    • Backbone or similar support around the nerve cord
    • Includes fishes, amphibians, reptiles, birds, and mammals
  6. Infraphylum Gnathostomata jawed vertebrates
    • Jawed vertebrates: jaws formed from gill arches
    • Paired fins or limbs
    • Includes all fishes except hagfish and lampreys, plus all tetrapods
  7. Superclass Osteichthyes bony vertebrates
    • Bony vertebrates: skeleton made largely of bone
    • Most have a lung or swim bladder
    • Includes ray-finned and lobe-finned fishes and all tetrapods
  8. Clade Sarcopterygii lobe-finned vertebrates
    • Lobe-finned: fleshy fins with bones like those of limbs
    • Includes coelacanths, lungfishes, and all tetrapods
  9. Clade Tetrapoda four-limbed vertebrates
    • Four limbs with fingers and toes (or descended from animals that had them)
    • Breathe air with lungs
  10. Class Mammalia mammals
    • Mammals: hair at some stage of life
    • Females nurse their young with milk (mammary glands)
    • Three small bones in the middle ear
  11. Superorder Laurasiatheria whales, carnivorans & kin
    • Large group of placental mammals including whales, carnivores, bats, and hoofed animals
  12. Order Carnivora carnivorans
    • Carnivorans: sharp cheek teeth for shearing meat (carnassials) in most
    • Includes cats, dogs, bears, seals, and weasels
  13. Suborder Caniformia dog-like carnivorans
    • Dog-like carnivorans: dogs, bears, weasels, and seals
  14. Family Mustelidae weasels & otters
    • Weasels, otters, and badgers: long bodies and short legs
    • Sea otters have the densest fur of any animal
  15. Genus Enhydra
    • Species in the same genus are very close relatives and often look alike.
  16. Species Enhydra lutris Sea otter

Closest relatives in the guide