This month I get to talk about one of my very favorite aquatic topics, the freshwater invertebrates. Invertebrates very simplified are animals without backbones (the vertebra). Approximately 95% of animals are invertebrates; they include mollusks, crustaceans, insects, jellyfish, anemones and worms among many, many others.

Most of the invertebrates are very tiny, microscopic animals. You probably have quite a few in your aquarium already and may not even know it. For right now though, I'll talk about some of the more visible invertebrates.

The first invertebrates that most aquarists encounter in the aquarium are snails. These are part of a group of animals called mollusks, most mollusks look like snails, slugs, oysters and clams but they also include octopuses and squids. The first recorded animals kept for aquaculture were oysters kept in the 1st century B. C. by a Roman.

Unless you take special precautions to keep them out, they will often show up in your aquarium whether you put them in there on purpose or not. The snails most likely to show up are ramshorns, pond snails or Malaysian livebearing snails. Snails do not like very soft water as they can't develop their shells.

Ramshorns describes a number of species of snail and probably crosses. These are small snails whose shells are flat sided and curled in the shape of a ram's horn, hence the name. The can be tan, brown, red, or spotted and many combinations. They are probably the most common ...