Why are the fish so colorful in the tropics and not so colorful elsewhere?
...Paul, Eastham, Massachusetts, USA
by Summer Collier, 10/11/98, South Caicos Island
All animals, including humans, need to communicate with each other. As humans our main form of communication is speech. We also utilize additional forms of communication such as body language and gestures. These ideas of primary and secondary types of communication correlate to all animals, including marine animals of the ocean.
Sound and colors are ways that marine fish communicate. All marine animals rely heavily upon sound because it travels so well through water. In areas of the world where the ocean is more temperate, meaning the water is cooler than tropical waters, the water is more turbid and visibility is low. In these areas, the fish are not brightly colored because colors cannot be seen very well (over evolutionary time the temperate species have developed silver and blue coloration as an adaptation). Because these marine fish do not use coloration for communication, they rely heavily upon sound for signaling, communicating and mating.
In the tropics, fish also rely heavily upon sound, but high water clarity aids visual communications. Sounds can be a signal to other fish, and once fish are in sight of each other, body coloration functions in the same way as an alternate, or secondary, form of communication to other fish.
What is your favorite animal so far?
...Gwen, Montreal, Quebec, Canada
by Jon Palma, 10/18/98, South Caicos Island
Of the many animals I’ve seen snorkeling and diving in South Caicos, I think my favorite is the black durgon. I usually see this type of triggerfish when we scuba dive at an old plane wreck off of Long Cay, one of our regular dive sites. Black durgon fish are predominantly black, but sometimes the area surrounding their eye is colorful: blue above, and yellow below. They also have the ability to change color and make themselves more pale or dark.
The reason that the black durgon is my favorite fish is because of the unique way that it swims. Rather than using its tail and pectoral fins to move, it predominantly swims with its top and bottom fins. The trigger is another unique feature of triggerfish, including the black durgon. It is basically a small retractable front dorsal fin. The black durgon uses its trigger to lock itself in a small crack in the rocks when it is frightened.
What kinds of animals and plants are on land on South Caicos Island?
...Edwin A., Tallahassee, Florida, USA
by Sarah McCarthy, 10/18/98, South Caicos Island
South Caicos has a very unique diversity of plants and animals. There are some trees on the island, such as Australian pines and mangroves, but most of the vegetation grows very low to the ground. There are different types of cacti and thorn bushes, as well as grasses and other ground cover.
Flamingos and other birds live in the salt flats at the center of the island. Each morning we wake up to the sound of roosters crowing. Horses, cows, donkeys, pigs, dogs, and cats can also be seen around the island. The donkeys are usually only seen on the uninhabited parts of the island, but the rest of the animals are seen everywhere. The domestic animals, like cats and dogs, and the livestock here are different from those in the United States because most of them roam around freely. It is hard to tell to whom they belong.