Seahorse Anatomy: In order to determine whether a seahorse is male or female and what type of species it is, it is important to know the something about seahorse anatomy.
The following illustrations and descriptions will help you learn the basics of the external anatomy of seahorses.
Seahorses have a long, horse-like head (hence their name) and a curled tail. Seahorses range in size from under a centimetre long (Pygmy Seahorses) to about 12 inches (30.5 centimetres) long.
Seahorses have armoured plates that cover their body (they do not have scales like other fish). The sections of a seahorse are the head, trunk and tail. The length of a seahorse is measured from the first trunk ring to the tip of the tail. The head is measured from the tip of the snout to just before the first trunk ring. The snout is measured from the tip of the snout to the gill opening.
Eye, nose, and cheek spines also differ in length from species to species. All seahorses have independently orbital eyes and a pair of pectoral fins immediately behind the gill opening.
The seahorses means of propulsion (process of propelling) are its pectoral fin, located just behind the gill opening and its dorsal fin, which joins the trunk at the tail.
On male seahorses, a brood pouch is found beneath the anal fin and when empty, tapers gradually to the tail.
During courting or when pregnant, the pouch is very pronounced and protruding.
It features a vertical opening into which the female deposits her eggs and from which fry (baby seahorses) emerge after gestation.
Some species of seahorses have spindly appendages, called cirri, in the area of the facial spines and trunk ridges.
The diagram on the left shows the areas of a seahorse and the terms used to describe them.
The front of a seahorse, looking into its face or belly, is the ventral view.
Looking from behind the seahorse is its dorsal view.
The sides are referred to as the lateral views.
The lower parts, or the lower section of any parts, are called the posterior and the upper parts, the anterior.