4 March: Fish

The current astrological sign is Pisces, which is a good enough excuse to present you with ten facts about fish:

1. There are approximately 32,000 different species of fish in the world, with more being discovered all the time. This is more than all the other kinds of vertebrates combined.

2. However, starfish, Jellyfish, shellfish, Crayfish/crawfish and cuttlefish are not actually fish. Their names derive from Old English from a time when every fully aquatic animal was deemed to be a fish.

3. The biggest fish in the world is the giant Whale shark, which can grow to nearly 60 feet, while the smallest is the Photocorynus spiniceps, a type of angler fish. The males are only 6.2 millimeters long.

4. As a fish grows, it doesn’t get more scales. The scales it has grow with it, and so it’s possible to tell how old a fish is by counting the rings on its scales.

5. Sharks are the only fish with eyelids, therefore the only fish that can blink.

6. The fastest moving fish is the sailfish, which can travel as fast as a car, and the slowest is the Dwarf Seahorse, which takes about one hour to travel five feet.

7. Fish don’t have vocal chords but they can make noises to communicate with each other. They rattle their bones, gnash their teeth or vibrate muscles against their swim bladders.

8. Fish have better memories and are more intelligent than we tend to give them credit for. Fish can recognise humans which feed them. Cleaner fish know the fish they regularly clean, which could be up to 100 individuals. The client fish, in turn, recognise individual cleaners. Fish can also learn how to use tools. Some use rocks to crack open bivalves such as clams, Oysters and mussels. Archerfish are able to learn how to shoot jets of water at insects above them by watching other archerfish do it. Fish can also remember Music; one group of researchers fed their fish while playing a specific song before releasing them into the wild. Five months later, the fish returned when the song was played at sea.

9. The only type of fish which can swim backwards are Eels.

10. The word for a large number of fish swimming together is a school. The movement of a school is controlled by the fish in the middle.