Order-Animalia: Scorpaeniformes

The Scorpaeniformes are a diverse order of ray-finned fish, including the lionfish, but have also been called the Scleroparei. It is one of the five largest orders of bony fishes by number of species, with over 1,320.

They are known as "mail-cheeked" fishes due to their distinguishing characteristic, the suborbital stay: a backwards extension of the third circumorbital bone (part of the lateral head/cheek skeleton, below the eye socket) across the cheek to the preoperculum, to which it is connected in most species.

Scorpaeniform fishes are carnivorous, mostly feeding on crustaceans and on smaller fish. Most species live on the sea bottom in relatively shallow waters, although species are known from deep water, from the midwater, and even from fresh water. They typically have spiny heads, and rounded pectoral and caudal fins. Most species are less than 30 cm (12 in) in length, but the full size range of the order varies from the velvetfishes, which can be just 2 cm (0.79 in) long as adults, to the lingcod, which can reach 150 cm (4.9 ft) in length.

One of the suborders of the scorpaeniformes is the scorpaenoidei. This suborder of scorpaeniformes are usually found in the benthic zone, which is the lowest region of any water body such as oceans or lakes. There are two groups of the scorpaenoidei. The sea robins is the first, which are further classified into two families: the sea robins and the armored sea robins. One significant difference between the two families of sea robins is the presence of spine-bearing plate on the armored sea robins which is absent in the sea robins family.

The second group of the scorpaenoidei suborder is the scorpionfishes, which according to Minouri Ishida's work in 1994 and recent studies, have twelve families. The scorpionfishes are very dynamic in size with the smallest one having a range of 2-3 cm, while the largest have a length of approximately 100cm.

Reference: Wikipedia