Reef Ecology Guide Phuket Thailand - Bony Fishes 1

Although both major fish classes have the same primeval ancestry, they have quite distinct characteristics. The bony fishes show an appreciably greater number of innovative features, which has led to explosive speciation: there are at least 36 species of bony fishes for every cartilaginous one.

Among other features, bony fishes evolved the swim bladder, an extremely useful piece of equipment, which enables its owner to maintain position without any energy expenditure and at any chosen depth. The swim bladder registers the change in pressure and automatically decreases or increases the amount of gas required to maintain the specific consistency of the entire organism against the water pressure at a selected depth. Cartilaginous fishes were not involved in this evolutionary process and to the present day have to make do without this buoyancy aid.

Unlike the solely carnivorous cartilaginous fishes, bony fishes have a wide range of food with plants, corals, flesh and plankton. Eggs of bony fishes get fertilized outside the female's body.
The advanced evolution of bony fishes has enabled them to occupy all ecological systems with many varied forms.

Families of eel like fishes, distinguished by continuous dorsal and pectoral fins, building a hemline with the tail fin. Instead of scales they have a thick skin. A layer of slime eases movement through sharp-edged corals and rocks.

These nocturnal hunters spend the day in crevices and caves. Moray eels are territorial and protect their habitat furiously against invaders. 

Scorpion fishes are a complex family with about 10 subfamilies. Scorpion fishes live close to the bottom, many of them well camouflaged and lurking for prey.

All species of the family possess venomous spines with a sting that produces extreme pain, followed by numbness. If stung, the best thing to do is to apply heat to the wound as soon as possible, and as hot as the victim can bear. Heat destroys the venom.

The Serranidae are a highly diverse family with several major groups, but classification is continuously under review. There are nearly 50 genera and well over 400 species, distributed worldwide.

The rock cods or groupers include larger fishes, sometimes of commercial importance. They feature tiny, embedded scales and as adults have small egg-shaped eyes. Most live alone and are territorial, claiming caves and the larger species claiming the greatest reef sections. Diet comprises a variety of fish, cephalopods and crustaceans.

The basslets are small tropical species, most of which are schooling planktivores but a few live on the substrate similar to the rock cods. They feature small sized ctenoid scales and large eyes. The caudal fin is usually deeply emarginated to greatly lunate.