A frog’s tympanic membrane, or tympanum, is the circular patch of skin directly behind its eye that we commonly call its eardrum. It functions much like our eardrum does –the tympanum transmits sound waves to the middle and inner ear, allowing a frog to hear both in the air and below water. In addition, this membrane serves to keep water and debris from entering a frog’s ears. In some species of frogs, such as the Green Frog, American Bullfrog and Mink Frog, their gender can be determined by the size of their tympanum relative to their eye: the male’s tympanum is larger than its eye, the female’s is equal in size or smaller than its eye.
Dragonflies (and bees) have the largest compound eyes of any insect, each containing up to 30,000 facets, or ommatidia (house flies have 6,000). Each facet points in a slightly different direction and creates its own image, and the dragonfly’s brain compiles these thousands of images into one picture. This eye structure enables dragonflies to be extremely sensitive to motion. Because a dragonfly’s eyes wrap around its head, it can see in all directions at the same time (though its forward-looking vision is the sharpest). When capturing prey, a dragonfly doesn’t chase it – it intercepts it in mid-air, and it’s successful nearly 95% of the time. This hunting technique entails calculating the distance of its prey, the direction it’s moving and the speed that it’s flying – an impressive feat any tennis, baseball or football player would especially appreciate!
(Photo is looking down on the eyes of a Common Green Darner. Three simple eyes, or ocelli, are located in the black section below (above in the photo) its two tan compound eyes. The short, thin black lines are its antennae, which can detect wind direction and speed. The yellow section is part of the upper half of its face, or frons.)
Do you know a 3 – 8 year old who loves animals and would enjoy getting close-up views of the antics of a red fox kit during the first summer of his life? My second children’s book, Ferdinand Fox’s First Summer, has just been published by Sylvan Dell in both hardback and paperback. I have been lucky enough to have had the opportunity to observe and photograph young red foxes as they interact with each other and with their parents. This book consists of a selection of these photographs, accompanied by text and an educational component at the end of the book. Look for Ferdinand Fox’s First Summer in your local bookstore. If they don’t carry it, you would be doing me a huge favor by asking them to. Thank you so much. My next children’s book is on Beavers and will be coming out in the spring of 2014. (I am still looking for a publisher for Naturally Curious Kids!)
Many snakes, including this Common Gartersnake, use smell to track their prey. In the roof of a snake’s mouth are two openings, called the vomeronasal organ, also known as Jacobson’s organ. Snakes smell by sticking their forked tongue in the air, keeping it constantly moving while they collect particles (mostly pheromones) on it from the ground, air and water. Next they pull their tongue back into their mouth and insert it into their Jacobson’s organ (one fork in each opening). Then the particles are analyzed and the snake determines whether prey or a predator is in the vicinity.
Being popular prey animals, white-tailed deer have evolved an extremely good sense of smell, sight and hearing. Their elongated noses are filled with an intricate system of nasal passages that contain millions of olfactory receptors – up to 297 million (dogs have 220 million, humans just 5)! As the tongue in this photograph infers, deer lick their nose to keep it moist, which helps odor particles stick to it, improving their sense of smell. Not only do deer use their sense of smell to avoid predators (including hunters), but they use it to communicate with each other, as is evident from the seven scent glands on their head, legs and hooves.