Vision

Frogs have large, well developed eyes that sit prominently at the tops of their head, offering most species the ability to see in any direction. Experiments indicate that frogs have excellent depth perception and are able to easily differentiate between prey and predator. They can see for vast distances. The eyes of tadpoles are located at the sides and tops of their heads and have less binocular vision than their adult counterparts. Based on the study of amphibian eyes, it has been determined that they have fairly good color vision. Tree frogs move toward green ( forested terrain) and aquatic frogs have a preference for blue light.

Olfactory Senses

Frogs have two basic organs for chemical olfaction or detection of odors. One is the epithelium of the nose, and the other is the Jacobson’s Organ, also known as the vomeronasal organ, located near the internal nostrils above the roof of the mouth. Airborne and aquatic odors are sensed mainly by the nasal or olfactory epithelium, whereas substances that end up in the mouth or on the tongue are sensed by the vomeronasal organs. The sense of smell is generally well developed and after sight, olfaction is the most important sense. The sense of smell in frogs has been linked to sex recognition, detection of breeding ponds, recognition of siblings, recognition of eggs, and recognition of individuals. It is also involved in delimiting territories as well as enabling prey detection, especially in low light or no light situations. Thus it is used in finding mates; avoiding enemies and helping amphibians find their way home, as well as getting a meal!

Hearing, Voice and Communication

Frogs and toads have well developed ears- including an eardrum that is visible behind the eye (tympanium) in some species. Frogs use their hearing mainly for one purpose: listing and communicating with other frogs. Amazingly, frogs even have dialects. For example frogs from a certain lake can distinguish the sounds of frogs from their own lake, and that of other frogs of the same species in a different lake, speaking the same language but with a different dialect. Frogs and toads communicate with each other by voice and in some cases by body language or movements. It is probable that frogs were the first vertebrates to communicate with each other by some sort of sound or speech. It is primarily the male of the species that has the best developed voice, as females are usually mute. Frog calls are most predominately heard during the mating season, the sounds are also known as the mating call. The sound is produced by the voice box or larynx which lies in the throat. Most frogs have vocal sacs that act as resonating or amplifying chambers.

Body Language

Some frog species have been observed waving their arms around in what certainly looks like some sort of signal, greeting, or similar form of communication. This was first observed by the small Australian frog. According to the observation, it appeared as these frogs were waving to each other. The purpose of such behaviors is not clear. It may simply be a muscle stretching exercise, or it may be some form of communication behavior or signal. It clearly resembles the hello/goodbye waving of people, and this makes it all the more mysterious.

Posted in Frog Anatomy

Like all amphibians, frogs need moisture. They leave water cautiously and most return to breed. Without moisture, their marvelous skin could not transfer oxygen from both air and water. Frog eggs are most particularly vulnerable to drying out for they have no protective shell.

All frogs are superficially of a simple design; they have few vertebrate ( five to ten) and the bones in their front legs and back are fused. In contrast, humans have 33 vertebrae, our lower arm bones are separated into radius and ulna, and our lower leg bones are separated into tibia and fibula. The two major bones in frogs are fused or partially fused. These particular features are adaptations to leaping and the stress that each landing will place on the skeleton.

The frog skull is a simple structure with virtually no neck, so almost all frogs must move their entire body to look in a different direction. In most species, nature has overcome this limitation by installing large, protruding eyes that provide almost 360- degree vision. Most species of frogs also have sharp eyesight, which helps guide their long tongues when they are capturing prey.

Frogs are ectotherms, which means that they obtain their heat from external sources. In contrast humans are endotherms, with an internal furnace that must be fueled daily to maintain a body temperature of around 37 degrees Celsius. Ectotherms are often called cold-blooded, but this term is a misnomer. Since their body temperature comes directly from the sun or from proximity to a heat source, on warm days ectotherms are warm. Moreover, cold blooded is a pejorative term implying cruelty and malevolence. I suspect, that the brain of a frog, does not contain room for these higher functions.

Because frogs cannot control their temperature internally, they do so behaviorally. During active periods of the year- usually the wet season in the tropics and the warm season in temperate areas- frogs select areas that provide heat but not too much heat. A move to the shade significantly reduces their temperature, as does a move into the water. This temperature control is critical because frogs that are too hot will die and frogs that are too cold will be unable to flee from danger or catch their prey.

Frogs that live in the temperate zone experience at least a few months every year when no source of heat is adequate to meet their needs. So they skip this season by hibernating. During hibernation, which may take place on wet litter at the bottom of ponds and lakes, they are very close to death. During hibernation, a frogs energy reserves remain largely intact for use during the spring to come.

Adaptations specific to Tree frogs

Treefrogs are obviously climbing frogs. They have special toe pads that allow them to cling to leaves, twigs, and tree trunks. Yes, what put the tree into treefrog? The toe pads did. Toe pads allow treefrogs to climb. Toepads are large, rounded tips on the treefrogs toes. The pads make it possible for treefrogs to cling to branches, leaves, or even glass. When a treefrog jumps onto a leaf, the toepads keep the treefrog from falling off. Toe pads are moist. This moisture allows them to cling to smooth surfaces. The moisture on toe pads is not sticky like glue. It is mostly water. Water can hold things together on its own.

Treefrogs can quickly change the tone of their skin from light to dark. Warmth and light backgrounds can make them turn light. Cold and dark backgrounds can make them turn dark. A few treefrogs can change colors. Gray tree frogs can turn from gray to green to blend in with leaves. The lemur treefrog can turn from a reddish color to green. Barking tree frogs can change from plain, bright green to green with dark spots. Most tree frogs are colored for camouflage. Their patterns and colors help them blend in with lichens, stones, leaves, or bark. The camouflage keeps them safe from birds and other predators that hunt by sight.

Tree frogs have big eyes to help them see better at night. Tree frogs are nocturnal, which means they are active at night. They find their prey by sight. They also make giant leaps from one twig to another. It takes a good eye to land safely. Big eyes can open wide to let in a lot of light. Large eyes also mean big retinas. The retina is in the back of the eye. It senses light and sends messages to the brain. A big retina helps a frog see in low light. The colored part of a treefrogs eye is called the iris. It opens wide in the dark of night to let in more light. It closes to a slit during the day to protect the eye from too much light.

Posted in Frog Anatomy

Frog skin is amazing! Find out why

1. The skin protects the animal against abrasion and infection from environmental pathogens.
2. Permits the exchange of respiratory gases (oxygen and carbon dioxide).
3. Permits absorption and secretion of electrolyte ions, thereby serving as an adjunct to the kidneys in maintaining correct electrolyte balance.
4. Permits absorption and release of water, thereby serving as an adjunct to the kidneys in maintaining correct water balance or hydrostasis.
5. Permits temperature regulation by lightening (reflecting heat) or darkening (absorbing heat) in some species.
6. Permits the animal to camouflage itself against its background in many species.
7. Brightly colored skins serve to warn potential predators of defensive noxious ore even fatal glandular skin secretions in a number of species.
8. Serves sensory functions: chemoreception, mechanoreception or tactile sensibility; and electrodetection in some fully aquatic species that retain lateral line organs in their skin.
9. Protects against cutaneous external and internal wound infection through the secretion of peptide antibiotics in some species
10. Liberates alarm substances in members of a population when one or more is attacked, thus alerting others to the presence of danger. Other odors associated with larval frogs are said to allow them to recognize their siblings as well as their birthplace.
11. Presence of coloration is designed to permit sexual recognition in some species.
12. Skin distensibility or elasticity permits prodigious feats of jumping, leaping, and even “flying” and landing without injury, often from substantial heights.

Posted in Frog Anatomy