The sea otter (Enhydra lutris) is more than just a cute face. This marine mammal plays a pivotal role in maintaining the health and diversity of marine ecosystems. From their unique behaviors to their threatened habitats, there’s a lot to learn and appreciate about these incredible creatures, and there’s no better time to do so than Sea Otter Awareness Week, which takes place during the last full week of September (September 24th-30th in 2023).
Introduction to the Enhydra Lutris Species
- Size and Physical Characteristics – Adult sea otters are typically between 40 and 65 inches long and weigh between 30 and 100 pounds, with males being slightly larger than females. They possess a dense fur coat — which is among the thickest in the animal kingdom (approximately 1,000,000 hairs per square inch) — to help them stay warm in their cold-water habitats.
- Dietary Preferences – When it comes to the sea otter’s diet, these animals are primarily carnivorous, feeding on a variety of marine invertebrates such as sea urchins, abalone, clams, crabs, mussels, sea stars, and fat innkeeper worms. Since sea otters don’t have blubber, they must consume 25%-30% of their body weight every day in order to survive in the cold waters they call home. Their diet is not just a matter of preference — it plays a crucial role in maintaining the health of kelp forest ecosystems by controlling populations of sea urchins and other herbivores.
- Lifespan and Reproduction – Sea otters have a relatively short lifespan compared to other marine mammals, living for about 10-15 years in the wild. Females give birth to a single pup after a gestation period of approximately six months. Twin births can occur in otters, but, sadly, the mother often abandons one of the pups in order to increase the survivability of the other. The mother takes on the primary role of caring for the pup, teaching it essential survival skills. Among the vital lessons are diving and foraging for food, ensuring the young otters can sustain themselves in their aquatic environment. Additionally, the endearing use of rocks as tools is passed down from mother to pup, allowing them to access hard-shelled prey with ease. However, this nurturing process is exceptionally challenging for the mother. Not only does she have to bolster her own metabolism to maintain energy, but she also has to feed and instruct her pup, which remains entirely buoyant for the first 8-10 weeks of its life, making the teaching process even more labor-intensive.
The Behavior of Sea Otters
- Social Structure and Rafts – Sea otters are social animals, often seen floating in groups called “rafts.” These rafts are usually gender-based — with groups typically consisting of either all males or all females — and can consist of a few to several hundred otters. They even have a tendency to wrap themselves in kelp to prevent drifting while sleeping.
- Mating Behavior – The sea otter mating behavior is complex and somewhat unique. Sea otter mating behavior is notably aquatic and can be intense. During the mating process, the male approaches the female from behind, grasping her face and nose with his teeth, sometimes even pulling her head underwater in an attempt to subdue her. This act can be quite violent and prolonged. Some female otters might form pair bonds with a single male, while others might mate with multiple males during one estrous period. The estrous period for female otters lasts several days and typically occurs once a year. However, if a female loses her pup before it reaches weaning age, she may enter estrus again and mate multiple times within the same year. This intricate and sometimes aggressive mating behavior underscores the challenges and complexities of sea otter reproduction.
- Behavioral Adaptations – One of the most fascinating sea otter behavioral adaptations is their use of tools. They often use rocks or other hard objects to open shellfish, a behavior that is not commonly seen in the animal kingdom. Floating on their backs in the water, they often use their chest or stomach as a makeshift table. After diving to collect hard-shelled prey like clams, crabs, or sea urchins, they lay the item on this “table.” To access the edible insides, the otter uses a rock, skillfully striking the prey in a manner reminiscent of a person using a meat mallet. This repeated hammering cracks open the hard shell, allowing the otter to feast on the soft flesh inside. This remarkable use of tools sets sea otters apart from most other animals and showcases their adaptability and intelligence.
- Grooming Habits – Grooming is a significant part of the daily routine for sea otters. Their fur is essential for insulation — it is incredibly dense and insulating, trapping a layer of air close to their skin to keep them warm in cold waters and prevent water from making direct contact with their skin — and keeping it clean and free from debris is vital for their survival. Part of their grooming process is to fluff the fur and blow in air to create the air barrier further enhancing the insulation properties of the fur.
Dive Into the Sea Otter Habitat
- Geographical Range – There are two main subspecies of sea otters and they have a vast range that stretches from the coasts of Russia and Alaska down to California. They prefer coastal habitats within a kilometer of the shoreline. The northern sea otter (Enhydra lutris kenyoni) is found in the Aleutian Islands, Southcentral and Southeast Alaska, British Columbia, and Washington. The southern sea otter (Enhydra lutris nereis) — also known as the California sea otter — lives in waters along the California coastline.
- Climate and Water Conditions – The sea otter habitat climate is typically cold, with water temperatures in the Pacific Ocean ranging from 35°-60°F (2°-15°C). Their dense fur and high metabolic rate help them survive in these conditions.
- Threats to Habitat – Sea otter habitat loss due to human activities such as coastal development, pollution, and oil spills is a significant concern. Conservation efforts are crucial to protect these habitats and ensure the species’ survival.
The Importance of Sea Otters
- Keystone Species – A keystone species plays a critical role in maintaining the structure, diversity, and balance of an ecosystem. Sea otters are often termed a keystone species because of their role in maintaining the health of kelp forests. They control the population of sea urchins, which are herbivores that can overgraze and devastate kelp forests if left unchecked, creating urchin barrens. This ensures the kelp ecosystem thrives and flourishes.
- Indicator Species – The sea otter serves as an important indicator species, particularly due to its diet of bivalves, which are filter feeders. As these bivalves filter water, they often accumulate parasitic worms and bacterial infections. Consequently, sea otters that consume these bivalves end up ingesting these harmful organisms. Ailments such as Toxoplasma gondii and Sarcocystis neurona are prevalent and well-documented in sea otters. The health and well-being of sea otters can provide insights into the overall health of the marine ecosystem, highlighting potential environmental issues and contamination.
- Biodiversity and Conservation – The presence of sea otters ensures a diverse and healthy marine ecosystem. However, their status as an endangered species highlights the urgent need for conservation efforts to protect these vital creatures and their habitats.
Sea Otter Awareness Week in September
Sea Otter Awareness Week in September (September 24th-30th in 2023, with the theme of Restoring Missing Links) serves as a pivotal platform for conservationists, researchers, and the general public to unite in their advocacy for this endearing yet endangered species. The week is packed with a myriad of activities, from educational workshops and beach clean-ups to virtual habitat tours and art contests. These events aim to educate people about the critical role sea otters play in marine ecosystems and the urgent challenges they face, such as habitat loss and climate change.
The impact of this awareness week extends beyond national borders, thanks to the global reach of social media and online platforms. It’s not just a celebration, but a call to action, influencing public policy through heightened attention and advocacy efforts. The ultimate goal is to galvanize collective action that ensures the long-term survival of sea otters, thereby contributing to the health and diversity of marine ecosystems worldwide.
By understanding and appreciating the complex behaviors, vital habitats, and ecological importance of the sea otter, we can better advocate for their conservation and ensure that future generations can also enjoy these fascinating creatures.
At Sea Otter Foundation & Trust, we work to ensure the survival and recovery of sea otters in their habitats by building funds to support research, conservation, and education. You can learn more about the all-important efforts of our grant recipients by watching our interviews with them. These efforts are funded directly by our supporters, so consider advancing our crucial work by adopting an otter or making a donation today!