Created: 5/17/2017 Updated: 5/18/2017
Looking at this picture, you might conclude that caterpillars have 8 pairs of legs- three pairs in the front, four in the middle and one at the back (if you're a bit confused, the head of the caterpillar is on the left in this photo). But wait, aren't caterpillars insects? Don't insects have 6 legs, not 16?
Like all insects, this caterpillar has only 6 legs. Note the different shape of the three pairs of legs near the caterpillar's head. They're the true legs. The remaining structures are not legs at all. They're protrusions from the caterpillar's abdomen called prolegs. Much like true legs, they help the caterpillar grip onto surfaces like twigs, and aid in locomotion.
Created: 5/16/2017 Updated: 5/17/2017
In this series, we'll be addressing some common questions from visitors and readers. Do you have a science question that has you stumped? Ask our museum scientists via our form here and we'll answer it on our blog!
Why do birds fly in formation?
If you've spent a year in the United States, then you've heard the honks and seen the distinctive v-shaped flying pattern of Canada geese. But geese aren't the only birds to fly in an orderly pattern: pelicans and ibises adopt the same v-shape when flying in flocks. What do these birds have in common, and what benefit do they gain from flying in a "v" shape?
Geese, pelicans, and ibises are examples of birds that migrate. Migration is the seasonal movement of animals in search of food sources or breeding grounds: geese fly south during the winter to find food and water; sea turtles travel between nesting sites on land and their feeding grounds on the coast; and college students return to their parents' homes in May when the cafeteria closes.
Those aren't geese: these Eurasian Cranes also adopt a v-formation when migrating.
Migration over long distances requires a lot of energy, so when migrating it is a great advantage for animals to save energy however possible. Animals will need less food, and the migration will take less time. That's where the v-formation comes in handy: scientific studies have shown that geese flying in formation may spend only half as much energy than if they flew alone or in some other shape. This is also why a squadron of jets will adopt the same v-shape: it takes less fuel for the aircraft to fly. Birds and jets are both able to gain extra lift by flying in the updraft that is created by the flyer in front of it.
Not all migrating birds fly in a v-shape: varieties of hummingbirds, finches, and sparrows all migrate, but these birds are too small to gain an energy-saving benefit from flying in formation. Not all migrating birds even fly, for that matter: the flightless emu from Australia migrates too, but does so on foot. And no, migrating emus do not run in formation.
But wait, there's more: There are other flying formations that the classic “v”! When birds flock in large groups in the air, this is also a deliberate formation. It's a defense mechanism that protects against predators: every bird is safer when they're in the flock. It's difficult for a predator to single out an individual from the flock, and a bird that leaves the flock is more likely to be eaten by a predator. The whole flock moves as one in order to protect every member. Starlings are well-known for their flocking behavior, and there is even a specific term -- a murmuration -- to describe a flock of starlings. It is absolutely worth watching this two-minute video from National Geographic to see a murmuration in action:
Nature Museum Volunteer
 Yong, Ed. “Not Exactly Rocket Science, A Blog by Ed Yong”. Birds that Fly in a V Formation Use An Amazing Trick. Retrieved May 5, 2017, from http://phenomena.nationalgeographic.com/2014/01/15/birds-that-fly-in-a-v-formation-use-an-amazing-trick/
 Cuttis, C.J. and Speakman, J.R. Energy Savings in Formation Flight of Pink-Footed Geese. Retrieved May 7, 2017 from http://jeb.biologists.org/content/jexbio/189/1/251.full.pdf
 The Nature Conservancy. “Managing Habitats for Migrating Land Birds in the Western Lake Erie Basin” (2008) https://www.nature.org/ourinitiatives/regions/northamerica/unitedstates/ohio/explore/bird-stopover-brochure.pdf
 The Animal Corner (2017). Retrieved May 14, 2017 from https://animalcorner.co.uk/animals/emu/
 Flight Plan. “How a Flock of Birds Can Fly and Move Together” (April, 2009) http://www.audubon.org/magazine/march-april-2009/how-flock-birds-can-fly-and-move-together
Do you have a science question that has you stumped? Ask our museum scientists via our form here and we'll answer it on our blog!View Comments