Along with penguins, polar bears, and baobab trees, there are some topics that I always assumed would never be the subject of this column. Dennis falls into that category.

The Grateful Dead were definitely not thinking of him when they sang, “What a long, strange trip it’s been,” but after recent events, it could have been this animal’s theme song.

Dennis was the 800-pound, eight-foot manatee sighted on the Cape last week. I say “was” because this story doesn’t have a happy ending. While Dennis made the trip north successfully all by himself via water, he perished on the way south surrounded by friends (US Fish and Wildlife Service biologists, Sea World marine mammal experts, and International Fund for Animal Welfare specialists). Truckin’ might have been the song that played on his road trip to Florida over land in a rented box truck. Tragically, he died on this voyage, only one hour away from his destination.

A manatee is a marine mammal that lives in southern waters, mainly Florida. Obviously Dennis didn’t know his geography, since he kept going north at Georgia until he reached the Cape. This was only the second time in recent history that a manatee was sighted this far into New England.

For this intrepid manatee who ventured north and kept going, the scenery might have been good and the food plentiful, but it was the temperature that was his undoing. Manatees cannot tolerate water that is less than 68 degrees, and local waters are currently a cool 60-ish degrees. When Dennis was taken out of the water, his body temperature was 24 degrees below normal. If water temperatures were higher, Dennis might have been able to make it home by himself; but with the cold water, survival was unlikely without human intervention.

The Cape has more experience with cold-stunned sea turtles and dolphins than with manatees, but in any case it’s a sad fate for those individuals who push the envelope of their habitat’s usual range. The evolutionary payoff, of course, for the ones who survive this risk is a potentially vast new region to conquer, with a useful head start on competition from others of their own kind. Perhaps, too, they range beyond the limits of their home waters just for the sheer pleasure of exploration — a travel bug, if you will.

Manatees are an endangered species in the United States. The current estimated population of these marine mammals stands at only 3,000 individuals, and the greatest threat to them is not cold water, but collisions with boats.

Also called sea cows, manatees are actually related not to cows, but to elephants. They can live up to 60 years, but have slow reproductive capacity. They birth only one calf at a time and their gestation period is one year. Their scientific order, Sirenia, is separate biologically from both the order of Cetaceans (whales and dolphins) and the sub-order of Pinnepedia (seals and sea lions), which form part of the order of carnivores.

Perhaps the most interesting aspect of their lifestyles is their eating habits, or more precisely, their teeth. Being from a dental family, I am fascinated by their choppers.

Manatees have marching molars, so called because their teeth grow from the back of their mouth and move to the front of their mouth. The manatee only has six teeth, and the one at the front falls out once it gets ground down. Luckily it is replaced by the ones moving from the back. These teeth are molars, and therefore flat. So they are well suited for the vegetarian lifestyle of the manatee, which eat a lot of roughage. Manatees consume up to 150 pounds of food per day, which can be up to 20 per cent of their body weight!

Maybe Dennis went astray because he was more focused on the salad bar than on the compass. Or maybe he was trying to find a way to a place where his species could flourish: his death was a huge loss for a species with so few individuals left. May he rest in peace in a warm, clean ocean with abundant plants and no motorboats, somewhere beyond the chilly New England waters of Cape Cod.

Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown.