I T WAS early summer and Father Stickleback darted about in his gayest suit. His cheeks and throat were gleaming red and his eyes shone like bluish-green gems. Most of his body was shiny green above and silvery underneath.
Unlike many fishes, Father Stickleback had no scales, but he did wear a row of bony plates along each side. These plates seemed like strips of enamel, and you may call them his coat of mail, if you like. Along the middle of his back was a row of stickles, or daggerlike spines. His jaws were short, though strong, and his teeth were sharp.
Father Stickleback built a nest. He brought bits of seaweed and fastened them to the lower stems of sea plants with tough elastic fibers, or threads.
The material for these fibers was made in a special gland in his body. While inside the gland the material was a liquid, but as soon as the fish spun it into the water it hardened to a fiber that he could use in building his nest.
Father Stickleback's building material may remind you of the silk that caterpillars and spiders make in glands in their bodies. Silk, too, is a liquid while inside the glands, and it hardens to a fiber as it is spun and touches air.
The little builder shaped his nest like a tiny muff. He made the inside smooth by swimming along the wall and pressing against it with his body. There were two round doorways just the right size for sticklebacks to use.
After finishing this very good nest, inside and out, Father Stickleback rushed off to invite a Mother Stickleback to lay her eggs in it. He swam beside her to show her the way. As soon as she had placed her eggs on the floor and had gone out through one doorway, Father Stickleback went in at the other and put some milt over them. Fish eggs, as you may know, need milt to make them grow just as plant seeds need pollen.
The nest was not yet nearly full of eggs. What could be done with all that extra room? It was not wasted. Father Stickleback hurried away and invited other Mother Sticklebacks to put their eggs there, too. So they came with him, one at a time, until the little nursery was filled with eggs almost to the doorways.
Father Stickleback waited near the home he had built, guarding it from snails and other intruders. When the eggs were about ready to hatch, he went into the nest and moved clumps of them, lifting them with his mouth and letting the water flow freely among them.
Father Stickleback guards his nest.
The eggs did not all hatch the same day. Some of Father Stickleback's sons and daughters were two or three days old before the youngest of the fry, or baby fish, were hatched. After moving about inside the nest for a number of hours, the older babies went to the doorway. The watery world looked pleasant as far as they could see, and after a little wait one of them slipped outside for a swim. He did not go far. Father Stickleback hastened after the tiny runaway, picked him up in his mouth, and took him back inside his home before he let him go. Soon another venturesome baby started out and had to be brought back in the same way. One after another those youngsters kept their father busy, but all the while he was careful and gentle. In all his hurry he did not bite one of them.
Within a few days, however, the last of the eggs were hatched and the whole family of little Sticklebacks, forty or fifty in number, were eager to leave their crowded nursery. So out they swam and this time their father did not take them back. He went with his brood, guiding the little fry from place to place. He protected them by swimming with them and keeping hungry creatures away.
This little father is only about three inches long and you might think to glance at him that it would be all he could do to take care of himself. He is not, however, so helpless as you may suppose from his size. He is not at all timid. He is brave enough to bite pieces from the fins of really large fish. Indeed, he can fight quite fiercely if necessary.
While the Sticklebacks are moving swiftly about the bay they often pass Hippo Campus, a little fish who looks so much like a horse that he is called "Sea Horse" for one of his names. He has no scales on his body, but he is protected by bony plates that cover him from the top of his head to the tip of his tail.
Yes, there he goes now swimming with his body held erect—head up and tail down. When he comes to rest he is likely to grasp the stem of some sea plant with his finless, coiled tail and hang head down. In this position does the queer little fish make you think of a monkey swinging from a branch by his grasping tail?
Hippo Campus does not become dizzy as he rests in this way. He does not suffer from a rush of blood to the head. He is perfectly comfortable. He looks about him and sees Mother Sea Horse hanging head down with her tail twisted around the stem of a neighboring plant.
Since it is time for Mother Sea Horse to lay her eggs, she drops them into the water. They sink to the sand beneath her and she does not need to pay any attention to them at all. Father Hippo Campus untwists his tail from the plant stem and goes down after the eggs. He picks them up and puts them into a little egg pouch on the under side of his tail. Then he closes the opening with a special sort of glue he has. The father fish hangs himself up again by his tail in a place where the sun shines on him and warms the eggs in the pouch. When it is time, the young hatch from the eggs and find themselves wriggling inside the dark, closed pouch. There they stay until they grow so strong that they can wriggle hard enough to punch an opening in the side of the egg pouch. Then out go the fry—a whole herd of tiny sea horses.
Father Sea Horse guarding young sea horses.
Ocean sticklebacks and sea horses do not travel far at nesting time. They do not leave sea water to spawn (lay their eggs). Their young, like those of many other fish, thrive in salt water. There are fish, however, that migrate, or travel, to fresh water before they spawn. The young, or fry, of such fish, start their lives in lakes or streams and seek the ocean when they need a change.
These migrants are not regular neighbors of the sea horses and sticklebacks. They are visitors from farther off the coast that enter Holiday Cove during their journeys. For a few weeks each spring they use the cove for a gathering place through which they pass on their way to Holiday Stream and Holiday River.
There are the smelts, for instance. They are most numerous during the flood tide of the May moon. These fish migrate in crowds, called schools, as far as the high tide reaches, and glue their eggs to stones where the fresh water of Holiday Stream will flow over them when the tide goes out. The father and mother smelts return to the sea with the ebbing tide. Their spawning trip is a short one.
The alewives, too, come hurrying into the cove every spring. They are members of the Herring Family, as you might guess from the shape of them. They go to the foot of the falls that pour out of Holiday Stream into the cove. In their eagerness to reach the fresh water they push together so tightly that not even little Father Stickleback could find room to slip between them. The dark fins on their backs show above the water like tiny sails. There they wait until the tide comes in and lifts them higher and higher, and then at last they can climb over the top of the falls and make their way up stream.
It is exciting to see the alewives scrambling over the top rocks of the little falls in the stream, but it is even more thrilling to watch the salmon in Holiday River. These spring migrants leave the ocean by way of the cove and swim to the rapids at the base of the falls in the river. There these leapers jump out of the water and over the rocks from place to place until they reach the river above the falls. Then they travel until they come to a quiet lake.
After all their rush to get into fresh water in the spring, it is not until late fall that the mother salmon lay their eggs and the fathers cover them with milt. There in the sand near the edge of the lake the eggs remain in cold storage all winter. When the ice above them melts and the water around them is warmed by the sun in the spring, the eggs hatch. The salmon fry live for a while in the lake and then, when they are old enough, they travel slowly down the river to the cove, and so on to the waters of the coast.
Atlantic salmon on their spring journey.
Of course Father Stickleback and Father Hippo Campus do not know that all the young smelts and alewives and salmon that come down stream and visit the cove for a while are the sons and daughters of the parent fish that hurry into the cove in the springtime. These little stay-at-homes know nothing at all of the habits of migrants that leave the sea and seek fresh water for the spawning season.