A Little Bit More
The treefrogs are found on all continents (except Antarctica) and vary quite a bit more in appearance and habitats than their name might imply. In North America their common names include the chorus frogs, cricket frogs, and treefrogs. These frogs are relatively slim-waisted, long-legged, and rather small, as frogs go. As our unit poster notes, these are not often seen because of their size, habitats, and/or nocturnal activity but they are often heard. In many cases, people hearing treefrogs are not even aware that it’s an amphibian calling.
Gray Tree Frog showing toe pads © Solon Morse
Although all of the treefrogs have toe pads, only those with large pads are able to navigate easily high in the trees to find insects. Those species with smaller pads are found closer to the ground or in some cases actually live at ground level. Treefrogs do need to find standing water for their eggs and young tadpoles to develop but once they’re mature enough to leave the water are often found some distance from standing water – some are even common in suburban areas.
It would seem that their toe pad adhesiveness might seem pretty straightforward but to date, scientists are not clear just how they function. Keep in mind that sticking to an object isn’t necessarily all that involved but being able to remove one's toes, once they’re stuck, requires a more complex anatomical arrangement and this is what we don’t yet understand. But whether we do or do not clearly understand the anatomy of their toe pads, they remain an interesting and enjoyable part of the natural world.
Activities
Science – Sticky Toes
Objectives: Better understand the “physics” involved in treefrog toe pads
Materials: Masking tape (single or double sided)
This is a simple enough activity that will help illustrate the logistics involved in a treefrog’s toe pads. As our Little Bit More portion notes, scientists don’t yet fully understand how a treefrog can both stick to an object (strongly enough to hold its own weight) and then remove its feet in order to crawl or jump. So, here’s an activity you can try with students that will show you why just being “sticky” isn’t enough.
1. Ask a student to be the demonstrator for a simple task
2. Use masking tape to make five rolls of tape around the finger tips on one hand with the sticky part out (if you use double face tape, this is easier to set up)
3. Have the student place all five taped fingers firmly on a smooth surface (table works well)
4. Once the hand is firmly placed, have the student raise ONE finger from the surface (this should be easily accomplished but will require some force to overcome the tape)
5. Now ask the student to replace the lifted finger and then remove all five fingers from the surface at once (again, easy enough to do but requires considerable force)
6. Point out to the students that if this person had toe pads like a treefrog, they would have enough sticky material on their fingers and toes so their entire body could be held on a vertical surface without falling
7. Ask the student if they were going to jump or crawl, would it have been easy for them to do so with their fingers/toes firmly attached to the table
I think this is a nice graphic demonstration of the physics involved. A treefrog must be able to both adhere to a surface strongly enough to hold on but then be able to extricate themselves when they need to move – not an easy task. This is what scientists have not been able to determine despite some rather sophisticated experiments.
Key Concepts
Structures and Functions, Identification, Behavior and Regulation, Adaptations and Diversity
Questions
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