A Little Bit More
As the unit poster points out, having common names can be both helpful and confusing for the public. Using scientific nomenclature (such as Homo sapiens for humans) for animals and plants is just fine for the scientific community, but once you get outside a more academic environment, it really isn’t feasible anymore. So, we use common names to label familiar animals and plants even though those names can vary from one continent to another or even one portion of a continent to another. As long as we use scientific nomenclature we’re all on the same footing (the Japanese and Chinese scientists use the same Latin names for genus and species as we do) and can understand each other but common names are a completely different matter.
Daddy Longlegs as Harvestman – these animals do look very much like spiders but have only one body part, and are actually more closely related to mites and ticks than they are to spiders. There are about 200 different species in North America and they feed on a variety of live and dead animals and plants; none is harmful and none makes a web.
Daddy Longlegs as Spiders – not all spiders have long legs but the cellar spiders or long-legged spiders have especially long legs. Cellar spiders are very common in peoples’ basements/cellars and are usually found hanging head down in the corner in a rather irregular web; none is harmful although their webs are a nuisance.
Daddy Longlegs as Crane Flies – the crane flies are an especially imposing insect since they look like giant mosquitoes. On close inspection it’s obvious that they’re flies (three body parts, six legs, and two wings) but they don’t bite humans or other animals so are harmless. North America’s more than 1,450 species of crane flies have especially long, delicate legs making the name Daddy Longlegs seem appropriate for this interesting animal.
So, the next time someone tells you they saw a Daddy Longlegs, be sure to ask them which one of the three they saw. You’ll probably get a blank stare but this will be your opportunity to fill them in on the three different kinds of “Daddy Longlegs” that you now know about.
Activities
Science & Math – Ratios
Objectives: Use math to determine anatomical ratios
Materials: Access to the internet
Although you can do this exercise quite well with access to your library, I’m going to provide you with all of the online addresses you’ll need to obtain the info electronically. If you prefer, you should be able to find plenty of photos in the library to do this project.
I’ve provided you with the names of a variety of animals that have long legs along with a web address so you can see each of these to make your own measurements.
1. Go online for each of the animals below and make two measurements. Measure the length of each animal’s body (head to tail) and length of one of its legs. (photo size doesn’t matter since we’re looking for ratios of leg to body, not actual life-size lengths)
2. Write down the measurements alongside the name of each of the animals so you know which is which (body length = X and leg length = X).
3. Once completed, go back to your measurements and change the figures into a ratio of the measurements that you found on each animal.
Example: Daddy Longlegs Spider – body (8mm) longest leg (50mm) ratio = 1/6.25
Daddy Longlegs Spider www.landcareresearch.co.nz
Daddy Longlegs Crane Fly www.uknature.co.uk
Daddy Longlegs Harvestman www.royalalbertamuseum.ca
Grasshopper tvindy.typepad.com
Cricket www.entomology.ucr.edu
Aphid www.westernhigh.org
Tiger Beetle www.kendall-bioresearch.co.uk
I’ve given you just a few invertebrate animals to measure but if you wish you can assign some mammals, birds, reptiles and others for your students to check out.
Special Note : Although the actual measurements that each student makes will vary – depends on the size of the photo they measure from – the ratios should be reasonably accurate for each species.
Key Concepts
Structures and Functions, Identification, Adaptations and Diversity
Questions
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