Context:
Recently, a study revealed that sea otters (Enhydra lutris) use tools like rocks to break open hard prey.
Key finding of the study
- Dietary Necessity: The diet of these marine mammals consists of shellfish which are rather hardy creatures, and so Sea Otters have learned to use rocks to bash open the shells to reach the juicy dinner inside.
- Technique: These clever mammals have been observed floating on their backs while using their chest as an anvil and a rock as a hammer to crack open clams and mussels.
Benefits of Tool Use:
- Larger Prey Consumption: Rocks allow otters to consume larger prey that might otherwise be inaccessible due to shell strength.
- Reduced Tooth Wear: By using tools to break shells, otters minimize the wear and tear on their teeth, preserving their chompers for other tasks.
- Sexual Dimorphism: Interestingly, the study suggests females utilize tools more frequently than males. This could be attributed to their smaller size and weaker bite force compared to males.
About Sea Otters
- Smallest Marine Mammal: Sea otters hold the title of the smallest marine mammal on Earth.
- Endangered Status: Sadly, these fascinating creatures are classified as endangered by the IUCN Red List of Threatened Species.
- Behaviour: Sea Otters are very social animals, and float in single-sex groups known as ‘rafts’. They are sexually dimorphic, meaning males and females have distinct physical characteristics.
- Unique Insulation: They do not have a layer of blubber like other marine mammals, and they rely on the layer of air trapped in their dense fur to keep warm.
- High-Calorie Diet: To maintain their body temperature in the cold water, sea otters consume a significant amount of food, ingesting between 25% and 40% of their body weight daily.
- Body fur: With up to one million hairs per square inch of skin, this species has the densest fur of any mammal.
- Adaptability: Its powerful forelimbs are well adapted for foraging on benthic invertebrates and its hind limbs are modified to function as flippers for swimming. They are adapted to a wide range of water temperatures.
- Habitat: Sea otters occupy coastal areas from the intertidal to at least 50m depths. The extent of their habitat is defined by their ability to dive to the sea floor for food with most foraging dives to depths less than 40m.
- Keystone Species: Sea otters play a vital role in their ecosystem. Their presence serves as an indicator of the overall health of the surrounding environment.
- Subspecies: Three recognized subspecies of sea otters exist:
- Enhydra lutris kenyoni – Found in British Columbia, Canada.
- Enhydra lutris nereis – Southern Sea otter or “California” sea otter.
- Enhydra lutris lutris – Russian sea otter.