Ovid opens his Metamorphoses with the line “In nova fert animus mutatas dicere formas corpora” (I intend to speak of forms changed into new entities), and that’s exactly what I intend to do today.
Ovid’s metamorphoses are largely concerned with one entity changed completely into another – Diana converting Actaeon into a stag after he had the misfortune of stumbling upon the goddess and her nymphs nakedly cavorting in a forest spring (he was quickly hunted down and killed by his own dogs); the hunky Adonis turned into the anemone flower by an adoring Venus after being gored to death by a wild boar; Perdix mercifully transmogrified into a partridge (the Latin genus name for partridge is, in fact, Perdix) by Athena after a jealous Daedalus chucked him from a high tower. (If Daedalus sounds familiar it’s because he was the father of Icarus, the boy who famously flew too close to the sun and melted his waxen wings, thus plummeting to a watery death. Hanging out with Daedalus apparently carried a serious risk of cataclysmic descent.)
But today I’m not talking metamorphoses mythical or metaphorical, but about teaching your kids about the physiological fundamentals of metamorphosis. Let’s keep it simple for the little ones, shall we? There are two main types of metamorphosis – complete and incomplete.
Most insects undergo complete metamorphosis, distinguished by 4 distinct phases – egg, larva, pupa, adult. Beetles, butterflies and moths, flies, ants, wasps and bees all follow this pattern. We’re undoubtedly most familiar with the butterfly life cycle. So familiar with it, in fact, that we may regard it with a yawn. But ponder it a moment, if you will.
A caterpillar emerges from a tiny egg and begins immediately to eat. And grow. A monarch caterpillar, for example, will increase its body mass by 2000 times in under two weeks. That’s the equivalent of a 7-pound (3.2 kilo) newborn turning into a 14,000-pound (6530 kg) toddler in less than a fortnight. That’s a big-ass baby.
Then a chemical process kicks in and it goes into its pupal stage. In butterflies this stage is called a chrysalis, in moths it’s a cocoon. Not much seems to be going on in there, but inside it’s a churning urn of activity, with organs morphing, migrating, developing. There’s magic transpiring deep within.
A short while later the chrysalis (or cocoon) cracks open and the insect emerges, pumps blood into its wings, warms up a bit, and flits off, a beautiful creature obsessed with sex.
Sure, it happens all the time, but it’s a pretty stunning stratagem nonetheless. And a successful one. The fossil record shows that insects have been around for roughly 300-400 million years. Anatomically modern humans? About 200,000. Insects may make up over 90% of animal life on Earth, and have been here perhaps 350 millions years longer than us. So have a bit of respect, okay?
Here’s a good informative video narrated by a little kid with funny hair.
Incomplete metamorphosis is not quite so dramatic, but fairly astonishing nonetheless. There are only three stages – egg, nymph, adult. Dragonflies, cockroaches, crickets and grasshoppers all demonstrate incomplete metamorphosis.The nymph looks more or less like a tiny version of the adult, but without wings. As the nymphs develop and grow, they shed their exoskeletons until their final molt, when the adults emerge to start looking for mates.
Then, of course, there are the frogs and toads. Watching frogs develop from egg to adult is fascinating, plus you get to say the word frogspawn which, you must admit, is kind of fun. The process is too familiar to require much explanation here, but this kid has made a great video that you can show your own kids.
So how do you best do a metamorphosis project with your kids?
Well, for butterflies and moths, it’s just a question of finding some caterpillars. Look carefully on plants in your yard, in some local woods, in a park or even on your own terrace. (We’ve had several species use the plants on our terrace for their egg-laying.) Caterpillars are often difficult to detect, but if you look closely for tell-tale droppings on the leaves, you know a caterpillar is nearby. (And since caterpillars eat a lot, they also poop a lot.)
Many species are specialists, laying eggs on only one variety or family of plants. Search for monarch caterpillars on milkweed, swallowtails on dill or fennel, vine hawk moths on grape vines, spurge hawk moths on spurge, etc. This site has a useful list of butterfly species and their corresponding host plants.
So now you’ve got your caterpillars. Place them in an aquarium or bowl (out of the sun or you’ll cook them) filled with a few branches and cuttings from the host plant arranged in a jar or cup of water. Cover your container, and place new cuttings in as necessary. In a week or so, your caterpillars should pupate. Then it’s just a waiting game. If you’re lucky, you’ll catch them as they’re just emerging, and will get to see them pump up their wings and prepare for flight. Release them immediately, or they’ll starve to death.
Dragonflies spend much of their lives in the nymph stage (some species up to 4 years), so are less suited to keeping at home. If you do want to collect and keep some, you’ll need a glass aquarium. Half-fill your aquarium with conditioned water then – and this is crucial – add plants, algae and water collected from the pool where you found the nymphs. Dragonfly larvae are voracious eaters, so they need to have suitable prey. Small fish will work, as will mosquito larvae, blood worms, or aquatic insects. Make sure there is a stick rising above the water so that when they do eventually become adults, your nymphs will have something to climb out on.
Frogs and toads are captivating to watch develop. Just don’t try to raise them with dragonfly nymphs, as we did. Tadpoles are nymph food. And don’t put their eggs in a tank with goldfish, as we did. Frog eggs are fish food. But if you avoid nymphs and fish, you’re good. Make the same setup as you would for the dragonflies, collect some frogspawn, and sit back and enjoy the show. As soon as your tadpoles have lost their tails and become adults, release them right back where you found the eggs; it’s really, really difficult to feed tiny frog-or-toadlets properly.
Well, I hope I’ve inspired you to do one (or all) of these projects with your kids. Metamorphosis is, to me, one of nature’s most marvelous, mind-blowing phenomena. Sharing it with your kids is even cooler.
PS: If you want to make your project a bit more academic, here are some worksheets for the kids.