Species
    Anurans is the collective name for frogs and toads. There are over 3700 species of anuran worldwide. Most of these are in the tropics. In New York there are 16 species of 4 families.
    Frogs and toads are highly adapted to a life of jumping and hopping. Few frogs walk exclusively, although the tree frogs are very good at climbing. The squat body seen in frogs is due to a reduction in the number of vertebrae. In the frog backbone there are only nine vertebrae, much fewer than in most other vertebrates. If you extend the leg of a frog, it appears to have two knees. The "second knee" is actually an extension of the foot bones. Frogs also have an external ear drum, called the tympanum, that is located just anterior to the eye. As amphibians, most anurans have slimy skins. The true toads (Family Bufonidae) are an exception to this rule.
    Many texts attempt to distinguish between frogs and toads. The only real difference is that what the layperson calls a frog and what the layperson calls a toad are members of different families. The spadefoots are sometimes referred to as toads, while the treefrogs are really neither frogs nor toads. The collective terms frog and toad are not valid in the taxonomic sense.  Anurans are carnivorous. They consume all variety of invertebrate and vertebrate life. Anurans will eat just about anything that will fit into their mouth even if that means eating one of its own kind. Many anurans and thier tadpoles are cannibalistic.

Terminology

• Dorso-lateral Ridge- the ridge on some frogs running from the rear of the eye to the base of the hind leg
• Paratoid Gland- the largest "wart" on the head of a toad or salamander
• Tympanum- the external structure of the ear drum found just caudal to the eye

Sound Production
    Anurans are unusual among amphibians in the dependence that they have on sound. In this respect they are more like birds than amphibians. It is mostly the males that call, although female frogs and toads have the ability to make some calls. The purpose varies by call, but those we are most familiar with are to attract females for breeding. Females have the ability to distinguish species based on sound, in fact, several species of anuran are most easily identified by their call. This is because of difficulty of locating the individual singer, and the similarity of external characteristics.
    As can be inferred by its breeding purpose, most vocalization occurs in the spring when mating occurs. Many species of frogs and toads have synchronized breeding. Because all of the individuals breed at once, the calls are heard for only a brief period each year. For other species, the songs may be heard throughout the season. Normally, there is a period of time in the spring where calling is the most vigorous and choruses of several dozen calling frogs can be heard, and after this some males will continue to call, but with less vigor and in less numbers.
    The sound is produced by forcing air over true vocal chords. The frog or toad first pulls in air through its nostrils, with its mouth closed. It then forces the air into vocal sacs located either on the floor of the mouth or at each shoulder, depending on species. The air is then pushed from these sacs through the larynx (where the vocal chords are found) which creates the sound. Contrary to popular belief, the vocal sac does not amplify the sound, but it does act as a resonator, giving the call its tone.
Although most calls generated by anurans are to attract mates, others are used for warnings. If you pick up a toad, it will emit several hoarse "barks" which are meant to signify displeasure. These calls are normally used to caution other males from entering the frogs territory, or are used as an anti-predatory defense behavior.
    As more research is being done on frog calls in the field, herpetologists are finding more and more calls with more and more purposes. Obviously, there is still much to be learned in this field.

Reproduction
    Reproduction in most anurans takes place in the water. The males attract the females with their call, and research indicates that females chose males based on subtleties in the voice that the human ear cannot pick up. Once the male's singing has attracted a female, he clasps the females in amplexus, similar to the salamanders. If the male attempts to amplex another male, the male being clasped emits a warning call, usually a high pitched scream, and the offending male will release his grip.
    Once the male and the female anuran enter amplexus, the female begins depositing eggs. In all but a few species, fertilization is external, the female releasing her eggs into the water and the male depositing sperm as she does so. The eggs are covered in a clear jelly-like substance that offers some degree of protection from the elements. The jelly also serves to fasten the eggs to the area in which they were layed. The shape of the egg masses can be used to tell once species from the next. For example, eggs of the American Toad are laid in long thin strings, while those of the Green Frog are left in a shapeless mass.

    Few frogs attend the eggs once they have been layed. The eggs develop quickly and in a few days to a couple of weeks the tadpoles emerge. Anuran tadpoles have large heads, small eyes, no legs, and a tail. A tadpole is really nothing more than a mouth and a stomach inside of a small package. Normally, tadpoles are herbivorous when young, but as they develop they eat more and more animal material as they near adulthood. Most species of tadpole are cannibalistic.

    After some development, which can take weeks, months, or even years, the legs begin to appear. First the hind legs appear and then the front legs. The tail is absorbed once the formation of the legs is complete. The young anurans are termed froglets (or toadlets) or metamorphs at this stage in their life. From here on they have the same natural history as the adult form.

Families
Anurans are classified in the Class Amphibia, Order Anura. This includes both frogs and toads. In our area, there are 16 species or subspecies of anurans comprising 4 families.

Family Pelobatidae- Spadefoots

• Eastern Spadefoot- Scaphiopus holbrookii holbrookii

Family Bufonidae- True Toads

• American Toad- Bufo americanus americanus
• Fowler's Toad- Bufo woodhousii fowleri

Family Hylidae- Treefrogs

• Northern Cricket Frog- Acris crepitans crepitans
• Cope's and Common Gray Treefrog- Hyla versicolor and chrysoscelis
• Northern Spring Peeper- Pseudacris crucifer crucifer
• New Jersey Chorus Frog- Pseudacris triseriata kalmi
• Western Chorus Frog- Pseudacris triseriata triseriata

Family Ranidae- True Frogs

• Bullfrog- Rana catesbeiana
• Green Frog- Rana clamitans melanota
• Pickerel Frog- Rana palustris
• Northern Leopard Frog- Rana pipiens
• Mink Frog- Rana septentrionalis
• Wood Frog- Rana sylvatica
• Southern Leopard Frog- Rana utricularia