CREATURES OF THE SEA:MARINE INVERTEBRATES
Invertebrates are those animals that have no backbone. Of the two
million species of animals in the world, 97 percent are invertebrates.
This includes insects, worms, and all microscopic creatures. Many
of these invertebrates live in the sea. There are thousands of different
species of marine invertebrates, ranging from minuscule plankton
to giant squid. |
species. Sponges and starfish are marine invertebrates. Sponges range in size from less than half an inch to over six feet. They don’t have true tissues or organs, and in fact, the sponge was believed to be a plant until the 1800’s. There are over 5000 species and some live at depths of more than 20,000 feet. They reproduce by releasing eggs and sperm to fertilize, and the larva floats as plankton until it finds a suitable place to attach itself to something, like coral, rocks, or plants. The sponge then remains in that one spot for its whole life, even providing temporary housing for an array of other animals, like shrimp and small fish. The starfish is a little more mobile, moving slowly along the ocean floor eating up dead material on the bottom, often referred to as the garbage men of the sea. A starfish can grow new arms if one is damaged; it can even grow a new body around one arm or a small body piece. In fact, before this fact was known, clam fisherman would cut up the starfish that they caught with their clams and throw the pieces back into the sea. They were trying to eliminate the competition and couldn’t understand why the starfish population exploded! Starfish can pry open a clam or oyster with their strong arms. Most species have five arms, but four and six are not uncommon and some have as many as 44 arms. Invertebrates aren’t all small creatures. Crabs can be ten feet across and lobsters can weigh up to 40 pounds. Then there’s the octopus and the giant squid, which can weigh over 1900 pounds. I think the octopus is one of the most fascinating creatures God has created. It is a mollusk, like the oyster and clam, |
although it doesn't have an outer shell. They are quite intelligent creatures, with a large brain proportionally. One in captivity unscrewed a glass jar to get to a crab inside, and they have learned to uncork bottles. Their long tentacles are strong and agile and can be used to pry open a clam shell and grip a rock to hide behind. The common octopus measures about three feet. There’s a tiny Atlantic pygmy octopus which is only about five inches across, while the giant squid may be 60 feet long! The octopus has the ability to change color to match its surroundings. Special pigment cells enable it to take on grayish, reddish or yellowish hues. The octopus can also squirt a black, inky substance as it darts away from danger. The ink vaguely retains the shape of the octopus and masks its retreat, and may even momentarily paralyze the senses of the predator. After mating, a female octopus will build a nest in a coral reef. For about two weeks she lays eggs and braids them like beads on a string hanging from the top of the den—like a beaded curtain. She will lay up to 100,000 eggs! Over the next two to three months she guards and cares for the eggs, using the suction cups on her legs like tiny vacuum cleaners. When the eggs hatch, each is a tiny, almost microscopic, whole octopus. The mother uses her jets to squirt water toward the den opening and the current carries the little guys out. 100,000 baby octopuses all emerging at once, choking up the ocean! Well, about half of them are eaten on their first day of life. Probably only two or three will ever become adults! The rest are simply part of the food chain, part of God’s provisions. Cont’d on page 4 |
