C ERTAINLY neither Stickleback nor Hippo Campus knows where the old eels are going when they pass through the cove on their way from the fresh-water in which they grew up to seek in the far sea places to leave their eggs. Yet the eels and their manners are worth knowing, for they are the most famous of all migrating fish. They depart in crowds from rivers that empty into the Atlantic Ocean and gather in the deep water between Bermuda and the Leeward Islands.
Eels and Sea Lampreys
There the father and mother eels spend their spawning season. So the young eels hatch from their eggs in that far-distant place. Do you suppose they stay there? They do not. They start in a northerly and westward direction while they are still very young. After living about a year in the sea, they enter the rivers the old eels left so long before. How do they find their way? Nobody really knows.
If you poke about among small plants near the shore, you are quite likely to find one of these little eels on his way to Holiday River. You may call him "Elver" if you like.
Elver is about two and a quarter inches long by the time he reaches the shore. He is colorless and as clear as glass, and his body is slender and round.
Before Elver reached Holiday River, his body had become slender.
He was not at all like that when he started on his long sea voyage. Indeed, during most of his journey, the baby eel had much the shape of the blade of a small pocketknife. He was as thin as a leaf. If you had placed his flat little body on this page you could have seen the black letters through it almost as easily as you can see them through a piece of clear glass.
Baby eels are thin and flat.
After you say good-by to Elver while he is wriggling slowly toward the mouth of the river, it will be several years (perhaps five or six) before he returns to the shore. If you and Hippo Campus see him then, he will be on his way, with a crowd of other eels, to the distant place beyond Bermuda where he was born.
Lamprel is not really a fish, as an eel is. He is a sea lamprey. However, his smooth body is almost as slippery as an eel's and he looks so much like an eel that people call him "lamper eel" or "lamprel."
Lampreys spend most of their lives in sea water, and like certain fish we have mentioned, they migrate to fresh water for their nesting season. You and Hippo Campus are quite likely to meet them at Holiday Shore in the spring of the year. Perhaps, then, you may wish to be introduced to Lamprel and learn how to tell him from an eel. That is more, by the way, than some people know.
Lamprel has no coat of scales on his naked, slimy body, but a lack of scales would not help you tell him from an eel, because an eel's scales are so tiny and so hidden in its skin that you would not notice them at all.
But Lamprel has no bones—and who ever heard of a boneless fish? Instead of a bony skeleton, Lamprel has only strong gristle for the firmer parts of his body. He has a nose with only one nostril. Instead of having gills, as a fish has, he has a row of seven slits on each side of his neck. Each slit opens into a little bag called a gill pocket.
This strange creature has plenty of teeth—nearly one hundred and fifty of them, in fact. They are hard, sharp, cone-shaped teeth, more like tiny pieces of horn than bone. Lamprel has no jaws to which they can be attached, so he wears them fastened to the inside of his mouth and on his tongue. He can neither bite nor chew, but he can cling to his food with his sucking mouth and scrape it to shreds with his many teeth.
Lamprel's sucking habits are useful when he travels or rests, as well as at mealtime. He cannot swim against a current of water as a fish can, for he has no paired fins or limbs of any other kind. He moves about very well without limbs, however. He can take a short plunge ahead even in a strong current, and then catch hold of a stone with his mouth and cling to it until he is ready to take another plunge.
Knowing how Lamprel anchors himself to stones, you may not be surprised to learn that one name for a lamprey is "stone sucker."
As likely as not, you may find Lamprel sucking a stone near Holiday Shore when he is about to start on his trip into fresh water to seek his nesting site. A crowd of other lampreys will be keeping him company. This will be in May, and while you watch the resting lampreys, schools of smelts and thousands of alewives may hurry past.
Slowly but surely—that is the way the lampreys travel. Even when they come to the falls over which the salmon went with such violent leaps, Lamprel and his companions take their time. It is now the darkest part of the night, but the lampreys are not discouraged. They need no light by which to find their way. They climb by plunging and clinging, little by little, until at last they reach the top.
Going over the falls is the hardest part of Lamprel's journey. One night, soon after that, a large fish swims near enough so that Lamprel fastens his mouth to the fish's side. As the fish is going up stream, Lamprel keeps his hold and rides for several miles.
When the migrating lampreys reach a rapid stream that empties into Holiday River they travel up that. On their way they meet some eels that will linger there until their migration time comes a few months later. Lamprel and the other father lampreys go a little ahead of the mother lampreys and pick out places for the nests. Each selects a rather shallow spot with a sandy bottom and plenty of pebbles.
By the time Lamprel has cleared the pebbles away from the sand where his nest is to be, a mother lamprey arrives and begins to help him. You may call her Agnatha, if you like. That name is an old word meaning "without jaws."
The current of the stream is so swift that the nest needs to be protected from it. Agnatha and Lamprel do this by piling stones at the edge of the nest to make a breakwater on the up-side of the nest and a little dam on the down-side. They keep hold of the stones, of course, by sucking them. Each can carry a stone as large as a hen's egg in this manner. Sometimes Agnatha and Lamprel both take hold of a heavier stone and carry it together.
When the circular nest, three or four feet across, is properly sheltered by the heaped stones, Agnatha and Lamprel go into the place they have prepared. Agnatha lays her eggs and Lamprel pours his milt over them.
What will happen to the young lamper eels that hatch from those eggs? Oh, more interesting things than we have space in this book to tell you about. They will undergo body changes as strange as that of a caterpillar becoming a butterfly or that of a tadpole becoming a frog. They will, in fact, be three or four years old and about five inches long before they can suck a stone like a regular lamprey. Then they will travel down stream from the fresh water of Holiday River to the salt water of Holiday Bay.
You may see them there, perhaps, before they pass on to deeper waters where they will stay until they are as old and as big as Lamprel and Agnatha. And then? Oh, then, of course, they will be ready for nesting time in May.