Skip to main content

Simple Reef Invertebrates

Simple Reef Invertebrates
There are millions of different kinds of animals in the world, yet they all have two basic characteristics in common. The first is that animals are multicellular organisms whose cells are organized according to their functions. In nearly all animals, groups of similar cells form tissues such as blood, muscle, and skin. Tissues are arranged into organs such as the heart, brain, and stomach. The second common characteristic is that all animals are heterotrophs. Animal tissues lack chlorophyll, so they are unable to use the Sun’s energy to manufacture food. For this reason, animals must find and ingest food.

Of the millions of species of animals in the world, 95 percent are classified as invertebrates. As the numbers suggest, invertebrates form a highly successful group that has adapted to every niche of the environment. The principal characteristic of animals in this group is the absence of a backbone, a column of vertebrae around a central nerve chord. To support and protect their bodies, many invertebrates are equipped with hard, external skeletons.

On the reef, the statistics of invertebrate success hold true, and the greater part of reef animals are invertebrates. They include very simple creatures, such as sponges, corals, anemones, jellyfish, and worms, as well as more complex groups, such as clams, snails, octopuses, lobsters, and starfish. While the most primitive reef invertebrates are barely more than colonies of cells, the advanced ones possess organs as sophisticated as those of humans.

Popular posts from this blog

Advantages and Disadvantages of an Exoskeleton

More than 80 percent of the animal species are equipped with a hard, outer covering called an exoskeleton. The functions of exoskeletons are similar to those of other types of skeletal systems. Like the internal skeletons (endoskeletons) of amphibians, reptiles, birds, and mammals, exoskeletons support the tissues and give shape to the bodies of invertebrates. Exoskeletons offer some other advantages. Serving as a suit of armor, they are excellent protection against predators. Also, because they completely cover an animal’s tissues, exoskeletons prevent them from drying out. In addition, exoskeletons serve as points of attachment for muscles, providing animals with more leverage and mechanical advantage than an endoskeleton can offer. That is why a tiny shrimp can cut a fish in half with its claw or lift an object 50 times heavier than its own body.
Despite all their good points, exoskeletons have some drawbacks. They are heavy, so the only animals that have been successful with them …

Differences in Terrestrial and Aquatic Plants

Even though plants that live in water look dramatically different from terrestrial plants, the two groups have a lot in common. Both types of plants capture the Sun’s energy and use it to make food from raw materials. In each case, the raw materials required include carbon dioxide, water, and minerals. The differences in these two types of plants are adaptations to their specific environments.
Land plants are highly specialized for their lifestyles. They get their nutrients from two sources: soil and air. It is the job of roots to absorb water and minerals from the soil, as well as hold the plant in place. Essential materials are transported to cells in leaves by a system of tubes called vascular tissue. Leaves are in charge of taking in carbon dioxide gas from the atmosphere for photosynthesis. Once photosynthesis is complete, a second set of vascular tissue carries the food made by the leaves to the rest of the plant. Land plants are also equipped with woody stems and branches that …

Prokaryotic Cell Structure

Prokaryotic cells are about 10 times smaller than eukaryotic cells. A typical E. coli cell is about 1 μm wide and 2 to 3μm long. Structurally, prokaryotes are very simple cells when compared with eukaryotic cells, and yet they are able to perform the necessary processes of life. Reproduction of prokaryotic cells is by binary fission—the simple division of one cell into two cells, after DNA replication and the formation of a separating membrane and cell wall. All bacteria are prokaryotes, as are the archaea.

Embedded within the cytoplasm of prokaryotic cells are a chromosome, ribosomes, and other cytoplasmic particles (Fig. 1). Unlike eukaryotic cells, the cytoplasm of prokaryotic cells is not filled with internal membranes. The cytoplasm is surrounded by a cell membrane, a cell wall (usually), and sometimes a capsule or slime layer. These latter three structures make up the bacterial cell envelope. Depending on the particular species of bacterium, flagella, pili (description follows)…