It’s the season of sea otters at the Detroit Zoo! Over the coming weeks, Dr. Ann Duncan, director of animal health for the Detroit Zoological Society, will be sharing updates about two of the Zoo’s newest inhabitants, Ollie and Monte. Read on to learn more about some of our favorite marine mammals!

A year ago, Detroit Zoological Society (DSZ) animal care staff was busy renovating a habitat at the Arctic Ring of Life to become home for two rehabilitated sea otters, female Ollie and male Monte.

As the DZS had not cared for sea otters in the past, the veterinary staff was busy learning about the animals’ unique anatomical and physiological features and medical needs so we could provide the very best care. We reached out to veterinary colleagues experienced in sea otter medicine and were able to take part in online learning opportunities. We also gathered and read the literature describing typical sea otter medical problems and treatment. 

Sea otters have several interesting adaptations, and caring for them is quite different from caring for similar animals, like North American river otters. Sea otters are in the water almost all the time, and when at the surface, they float on their backs. Unlike other marine mammals, sea otters don’t have fat under the skin for insulation. They instead rely on a unique hair coat and high metabolic rate. They have the thickest hair coat of any mammal — more than a million hairs per square inch! The hairs have tiny scales that interlock to form a dense, felt-like barrier that traps air and keeps the skin from becoming wet. This special coat is maintained by fastidious grooming, and when sea otters are not foraging or sleeping, you can usually observe them using their forepaws, flippers and tongues to care for their coat. Without a healthy coat, sea otters will lose heat to the water and cannot survive. When drawing blood, performing surgery or doing ultrasound, we avoid clipping any hair so that there won’t be a window for heat loss. Since the arrival of Monte and Ollie, we have regularly taken images of their hair coats using a thermal camera to look for any areas of irregular heat loss. So far, they have been perfect!

The metabolic rate of sea otters is eight times higher than the standard metabolic rate of similarly-sized terrestrial mammals, and they forage as often as every four hours and eat about 20 to 25 percent of their body weight in food each day. To meet these needs, we feed our sea otters at the zoo six times each day. Digestion of food generates heat and is an important strategy for maintaining body temperature while in cold ocean waters. We analyze the nutrient and energy contents of all the food items we feed to our sea otters and weigh them frequently to make sure they are meeting these high energy demands. 

Sea otter skin is very loose, and they have two loose pouches of skin near their arm pits that they can use for storing and carrying food and other items. 

Sea otters don’t have the best vision, but their eyes are uniquely adapted to allow them to see well both above and below water. Their ability to accommodate in this way is three times higher than reported in any other mammal.  Sea otters close their ears and nostrils when diving. Their noses contain a complex labyrinth of turbinates that serves to increase the surface area for warming inhaled air as it enters the body and allows otters to have an excellent sense of smell. 

Males are larger than females, weighing up to 100 pounds, compared to 75 pounds for females. Their lower incisor teeth are chisel shaped and protrude so they can be used to scrape food out of the shells of their prey. Their molars and premolars are wide and flat, perfectly shaped for crushing hard foods like clams and sea urchins.     

My favorite sea otter adaptation is that they are cute! Sure, from a veterinary perspective, they are interesting, but they are also absolutely adorable. It’s impossible to watch them swim and interact without smiling, and it’s easy to want to do everything possible to help them thrive. All sea otters in human care have a medical condition that jeopardizes their ability to survive in the wild. I am proud of the Detroit Zoo for making a commitment to support the rescue and rehabilitation of stranded or injured sea otters by providing a long-term home for those who cannot be released. While we currently only care for Monte and Ollie, we have the space and resources to offer safe refuge for additional animals when needed in the future. 

Stay tuned for my next blog, where I’ll describe a recent trip to the Monterey Bay Aquarium for sea otter medicine boot camp. There, I was trained firsthand how to restrain and perform anesthesia on these beautiful and unique animals.

– Dr. Ann Duncan is the director of animal health for the Detroit Zoological Society.