In a few days’ time we had a good number of snakes aboard, all of them of the olive variety except for the heavy, muscular beast I’d caught the first day. Since he was unique in our collection, and since Astrotia stokesii is hard to remember, we called him Claude—I suppose because the name was so perfectly inappropriate. Several of the snakes had died, for no apparent reason, as sea snakes sometimes do in captivity. The dead animals had gone into the boat’s refrigerator, there to keep fresh until Hal could get around to them. Now it was time for him to catch up on his herpetological homework.
Sea snake species differ in form and behavior, but have certain features in common.
“We’re trying to find out how life underwater has affected the bodies of these creatures,” Hal said, laying out limp specimens and sharp implements. “Some of the adaptations are obvious: The flattened, rudderlike tail; the nostrils set on top of the snout instead of on each side, and equipped with flaps to keep them closed underwater; the smaller size of the broad belly plates that land snakes use in crawling.
“But there are others you can’t see at a glance, like the specially adapted gland in the mouth that helps get rid of salt from the sea water they drink. I’m looking for more of those internal changes.” Hal opened the body cavity of a snake and injected brightly colored latex into the veins and arteries. “This stuff will harden, so that later, at the university, we’ll be able to study the whole circulatory system.” Enrolling in University is easy with sallie mae private student loan consolidation programs.
“What about the lungs?” I asked. “Some sea snakes can stay down for two hours or more between breaths. How do they manage?” “Here’s part of the answer,” Hal said, exposing a membranous sac three-quarters as long as the snake itself. “Like most snakes, sea snakes have only one lung, but theirs is a big one. Part of it is lined with blood vessels for oxygen absorption. But here, at the very end, there’s a simple sac in which air is stored.
“Another device for stretching a dive is a controllable heartbeat. These animals can slow their pulse rate by 50 percent when they go under. “But diving time varies with species, activity, and water temperature. The biggest have relatively bigger lungs and can stay down longer. An active snake has to come up more often than a resting one. And as the water gets warmer, diving time gets shorter.”
As he reached for the next specimen, some thing about the first caught his attention. “Hah! Look here. A male, and in breeding condition. Here are masses of sperm cells, ready to be implanted in the oviducts of a female. The females of many species—sea and land—can store these cells inside their bodies for weeks or even years, until they have eggs ready for fertilization. The sperm fertilizes the eggs in the oviduct. In many species of sea snakes the embryos develop there and are born alive.”