An online resource based on the award-winning nature guide

Posts tagged “Bufo americanus

American Toad Parotoid Glands

7-5-17 parotoid gland - A.toad 055

One of the adaptations that allowed the first amphibians to spend time on land was their skin, as it helped prevent them from drying out. It also served as an effective defense mechanism.

The skin of the American Toad contains multiple glands, both mucous and granular. Mucous glands are scattered all over a toad’s body and secrete a transparent mucus secretion that acts as a lubricant in water and also helps keep their skin moist on land. Granular glands contain a toxin that deters many predators, and is a toad’s main way of defending itself. (In addition, the toxin also protects a toad’s skin from microorganisms as well as helps repair wounds.)

Sometimes clusters of granular glands form a pad, or “macrogland.” American Toads have two such pads, or s parotoid glands, which are located behind their eyes. When threatened, a toad adopts a defensive stance, inflating its body and standing with its hindquarters raised and its head lowered, a position which makes its parotoid glands the first thing that an attacking predator encounters. The secretion from these glands generally induces very serious inflammations of a predator’s eyes or digestive tract, as well as vomiting. Some predators are immune to this toxin, while others, like the American Crow, have figured out a way to prey on toads without consuming any poison — it punctures the toad’s skin with its beak and then pecks out the toad’s liver without ingesting any toxin.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


American Toad Eggs Hatching

6-3-16  toad tadpoles 036

American Toads lay their eggs in double strings (one from each ovary) which can be three or more feet long and may contain 4,000 – 8,000 eggs.  It doesn’t take long for toad eggs to hatch – just one week, or two at the most.  The gelatinous strings begin to disintegrate, and tiny, dark tadpoles are released into the water. If nothing untoward occurs, the tadpoles will attach themselves to underwater vegetation or their egg mass for a few days, and hang vertically with their heads up.

Many aquatic predators, including Eastern Newts, consume both American Toad eggs and tadpoles.  The pictured newt waited patiently nearby until tadpoles wiggled their way out of the gelatinous egg string and then immediately snatched and ate them. In another week toad tadpoles will be crowding the shallow shoreline water, and in two more weeks they’ll be metamorphosing into little toadlets.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com  and click on the yellow “donate” button.

 

 


Toadlets Dispersing

7-17-13 toadlet 021The American Toad tadpoles that hatch in May and June begin to transform into toadlets after about three weeks. Metamorphosis is a complex series of changes both external and internal. Lungs are formed, gills are absorbed, the digestive system changes from a primarily vegetarian one to a carnivorous one, legs appear and the tail is absorbed. When these changes have taken place, the toadlets leave the water but tend to linger near the pond for days or weeks. Eventually they disperse, and by July you start finding small toads in the woods and around your lawn and gardens.


American Toads Calling

5-13-13 A. toad singing2 096Most of us are familiar with the American toad’s breeding call – a long trill that advertises his presence to potential mates in the area. However, American toads have three other calls, as well. A shortened version of the courtship trill, which sounds like a chirp, is given by male toad with its vocal pouch just slightly inflated. A second, release call, is often heard when a male is clasped by another male. (If you want to hear it, just pick up a male toad during the breeding season – it will vibrate as it chirps right in your hand. The combination of the call and the vibrations usually causes a clasping male to release his grip.) A fourth call, which has been recorded in the lab but not in the field, is a series of quiet clicks given by the male while clasping a female.


How Toads Breathe

Like all amphibians, toads breathe through their skin as well as with their lungs. When a toad is inactive the skin usually absorbs enough oxygen to meet its needs. During and after activity a toad often supplements its supply of oxygen by actively breathing air into its lungs. Unlike mammals, amphibians do not make regular and rhythmic breathing movements but bring air into their lungs spasmodically as the need arises. Air enters the toad’s mouth through its nostrils, and by raising the floor of its mouth, the toad forces the air into its lungs. (Photo is of an American Toad.)


AMERICAN TOADstool

Look closely at the base of this fungus for its true namesake.