NATURE NOTES FROM ACADIA

GIANT SEA TURTLE

When, on the sixteenth day of August, Mr. Charles L. Bowen of Rockland, Maine, went to tend his lobster traps at Roaring Bull Ledge, Isle Au Haut, he was amazed to find a huge black form thrashing about in an endeavor to free itself from ropes which led from the buoys to the lobster traps. After considerable effort, the fisherman succeeded in getting a line around the animal's body, and in due time it was towed to Rockland where it was placed on exhibit.

Since the animal had been caught in ocean waters which are but 20 miles to the southwest of Mount Desert Island, I hurried to inspect it. Much to my surprise I found a gigantic sea turtle with dark paddle-like flippers, a coal-black prominently-ridged carapace, and a massive egg-shaped head. Mr. Bowen informed me that now, after having been eviscerated, this patriarch of turtles weighed 635 pounds. Such a figure would indicate a live weight of approximately 800 pounds.

This species, the Leatherback Turtle (Dermochelys coriacea), represents the largest of the sea turtles. Laying my tape measure over the middle keel of its shell, I found that the specimen in question was 7 feet 8 inches from the blunt tip of its nose to the point of its tail. The shell or carapace, a black leathery armor traversed by seven pronounced bony ridges which ran its entire length, measured 61 inches along its middle keel. The front flippers, powerful swimming organs, each measured three feet from bend to tip and were 13½ inches in width. The rear flippers, though just as wide, were smaller, measuring 21 inches in length - a pair of very effective rudders. Unlike the flippers of other marine turtles such as the Loggerhead and Green, the flippers of the Leatherback r e not covered with plates or shields.

In view of the possibility that this specimen might find a final resting place in the museum which we hope will be built in Acadia National Park, I have been interested in the records of other large individuals of its kind. Dr. Harold L. Babcock, Curator of Reptiles and Amphibians, Boston Society of Natural History, makes the remark* that a reliable average for most adults is about six or seven feet. He gives the following interesting records:

"Gadow (1901, p. 333) states that the biggest specimen in the British Museum is about six and one-half feet from the nose to the end of the shell, which latter is about four feet. Ditmars (1907, p. 6) describes one in the American Museum of Natural History with a total length from snout to end of tail of six feet, length of carapace five feet one inch. Sears (1886) measured one with a total length of seven feet three inches. The largest specimen in the Museum of the Boston Society of Natural History has a total length of eighty-three inches and carapace of fifty-seven inches." Dr. Babcock, in a recent letter to the writer, states that the specimen in question is unusually large.

In his work on the fossil turtles of North America,* Mr. Oliver P. Hay remarks that the Leatherback is "the most thoroly aquatic turtle that is known." It is probable that the males never leave the sea whereas the females do so only to lay their eggs. It inhabits tropical and semi-tropical seas and, being a great wanderer, occasionally strays to far corners of the earth. Dr. Babcock writes, "It occasionally visits the coasts of Great Britain, France, and the Mediterranean, but is more common in the western Atlantic from Florida to Brazil, - the West Indies, according to Agassiz, being its home. It has been taken off the coast of Japan and in the Indian Ocean... These turtles from time to time travel north in the Gulf stream, leaving it as it turns eastward, thus coming in contact with colder waters, and so appear occasionally along our middle Atlantic and New England coasts, often in a chilled and benumbed condition."

Rarely do these giant turtles wander as far as the coast of Maine. Mr. Arthur H. Norton, Curator, Portland Society of Natural History, has sent me records the earliest of which goes back as far as the year 1863, and in all that time but 18 or 19 individuals have been listed. A large number of these are from the region of Casco Bay, near Portland.

As to its food, Dr. Babcock writes that sea-weeds, crustaceans, molluscs, and fishes are considered its chief diet.

Dr. Raymond L. Ditmars** places this turtle in a suborder by itself "because the vertebrae and ribs are not rigidly attached to the carapace as with all other Chelonians. The carapace and plastron are actually composed of a large number of irregularly-shaped plates; except where those protrude - on the upper shell - in the shape of keels, or heavy ridges, they are imbedded in the oily, fatty substance, like whale blubber, that externally presents a leathery appearance and suggests a popular name for the animal."

"The position of this species in the evolutionary system," writes Dr. Babcock, "has been a much debated subject. One group of naturalists considers it the sole remnant of a primitive group, while another looks upon it as a most highly specialized descendant of the Chelonidae."

-Arthur Stupka