The anatomy of the frog, as we envision it, comprises longer hind legs, webbed feet, a short body, protruding eyes, and lack of a tail. This semi-aquatic creature is spotted on land as well as in water. This ability is manifested through an anatomy designed for both, jumping or leaping on land, and swimming in ponds and lakes. The young ones or tadpoles are born and develop in an aquatic environment. Most adult frogs have a carnivorous diet, comprising gastropods, arthropods, and annelids. The croak, the leap, and the skeleton are quite unlike any other creature on the planet.
Frogs commonly inhabit the tropic and subarctic regions and the tropical rainforests. These amphibians 'lose' their tails as adults, and develop legs that are more suited to jumping, than the regular walking gait commonly observed in the case of other terrestrial creatures. Their physiology differs from that of terrestrial vertebrates. They breathe through their skin, which is highly permeable.
Oxygen from the terrestrial and aquatic environment gets dissolved within the aqueous film on the frog's skin. It is then transported to the blood. This process of blood oxygenation is responsible for the moist skin of the amphibian. This same feature also makes the frog highly susceptible to toxins in the environment.
Frogs have elongated ankle bones and forelimbs that are shorter than the hind appendages. This feature is responsible for the leap instead of a walk. The short vertebral column consists of not more than ten free vertebrae. The trunk ends in a fused tail-bone or coccyx, giving the amphibian a tailless phenotype.
The skin is not held to inner muscle and bone by taut connective tissues. This results in loose and limp skin texture. The outer appearance highlights folds, warts or a very smooth skin, features that largely depend on the region of inhabitation. The eye structure comprises a transparent membrane to protect them underwater, and two translucent or opaque membranes for both, terrestrial and aquatic use.
The tympanum on either side of the head enables the sense of hearing. Frogs do have a ridge of small, cone-shaped teeth, mostly in the upper jaw edge. These maxillary teeth and the vomerine teeth on the palate do not in any way assist the tearing or chewing of food. These amphibians swallow their food whole. The teeth only help in obtaining a better grip on the morsel.
The anatomy of the frog's legs highlight features that enables the creature to burrow, move swiftly, and prey or escape predators. The numerous adaptations that have consistently evolved help them in locomotion and survival. They have webbed toes and toe pads, that help them to grip vertical surfaces. The pads at the ends of the toes are naturally endowed with interlocking cells that grip substrate irregularities.
This amphibian now exhibits adaptations such as:
- Fused tibia, fibula, and tarsals into a single bone.
- Fused radius and ulna into the forelimbs.
- Elongated metatarsals integrated within leg-length.
- Elongated ilium into a mobile joint within the sacrum.
Many frogs are poisonous and unpalatable to predators, due to the presence of toxins in the parotoid glands. They have chest muscles that are not involved in respiration, and a three-chambered heart that gives them a higher metabolic rate. Frogs have ten cranial nerves and ten pairs of spine nerves. They lack external ears, but have tympanic membranes that enable body control, balance, and orientation. The species existent today display musculoskeletal morphology that has naturally modified for centuries.