What's the Difference Between a Bug and an Insect?

Welcome to What’s the Difference, the newsletter committed to bringing you a decisive hit of random, wholly unseasonal knowledge in spite of the thrum of season’s greetings and BOGO deals and shipping notifications overtaking your inbox. Because let’s face it: you probably thought insects and bugs were the same thing, right?? Spoiler: THEY’RE NOT. Read on, my little elves. 

In classic biology taxonomy, all insects belong to a class called Insectasix-legged organisms with three-part bodiesjointed legstwo antennae, and compound eyes (visual organs made up of many visual units clustered together, all with their own corneas and lenses). Insecta falls within the phylum Arthropoda: cold-blooded creatures with an exoskeleton and no backbone. Your classic insects include bees, mosquitoes, butterflies, and ants—all of which fall into a variety of orders/families/genuses/species within the Insecta category.

One of those orders is called Hempitera, and it’s where the bugs live. Bugs are types of insects with certain defining characteristics: 1) They have a mouth shaped like a straw, called a stylet, that’s used to suck up juices from plants or blood from other insects or animals. 2) They have no teeth. 3) They have some weird stuff going on with their wings: their front wings are thickened and colored where they attach to the body and taper out towards the back end of the wing, and their hind wings are usually clear and tucked under the front wings. Some example of true bugs include beetles, stink bugs, and cicadas.

If you’re paying attention, you’ll notice that there’s been no mention of spiders, and that’s because…spiders aren’t insects! Spiders, ticks, mites, and scorpions all belong to a class called Arachnida, a separate class from Insecta within the Arthropoda phylum. Arachnids have eight legs instead of six, two-part bodies instead of three, and simple eyesinstead of compound eyes. They also have different dining rituals: to eat, they inject digestive fluids into their prey before sucking up the liquefied remains. 

So, in summary: All bugs are insects. All insects aren’t bugs. And arachnids are their own separate category, with table manners that I’m looking to for #inspiration this holiday season. Bon appétit!

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What's the Difference Between Alligators and Crocodiles?

If humans were around 230 million years ago, and they had computers and email addresses and newsletters devoted to random facts delivered to their inboxes each week, they’d be asking this same question—because alligators and crocodiles, part of the Crocodilia order of reptiles, have been around for that long. That means that they’ve been here since before the dinosaurs, before the ice age, and before everything that came after that. 

And yet: we’re here, in 2018, and we still don’t know the difference. That’s about to change. Let’s get into it! 

Habitat: Crocodiles have a special gland in their tongues that can expel a large amount of salt, so they usually reside in saltwater habitats (such as mangroves and estuaries). Alligators don’t have this gland, so you’ll usually find them in freshwater.

Jaws: Alligators have wide, U-shaped snouts; crocodiles have pointier, V-shaped snouts.

Teeth: When a crocodile’s mouth is closed, the fourth tooth on the lower jaw sticks out above the top lip—but when an alligator does the same, all of its teeth are covered. Also: alligators’ upper jaws are wider than their lower jaws, which means that if they gave you a smile, you’d only see the top row of teeth. Crocodiles, on the other hand, have a toothier grin; their jaws are about the same size as each other, and when their mouths are shut, their teeth interlock. 

Skin: Both alligators and crocodiles have small, pit-like marks in their skin called integumentary sense organs, which act as motion detectors and allow them to feel for prey in muddy water. These organs, which look like small dots, are only on the alligator’s jaw—but they cover the entirety of a crocodile’s body.

Limbs: As discovered this year by researchers in Japan, alligators tend to have shorter humerus bones in their arms (or forelimbs) and shorter femurs in their legs (or hind limbs). This gives them a different gait than crocodiles; smaller crocodiles have been seen to bound and gallop on land, while alligators move in a more crawl-like manner. 

We could leave it at that, but in my extensive Crocodilian research, I found some of their similarities to be even more intriguing than their differences. Read on, if you dare:

  • Crocodilians go through up to 8,000 teeth in their lifetime, and they can chomp through pretty much anything: a crocodilian bite can produce up to 5,000 pounds of pressure per square inch, as compared to the 100 pounds that a human jaw can generate. 

  • Because both alligators and crocodiles are carnivores, they have particularly powerful senses. This translates into super-sharp vision, especially at night—their vertical pupils let in more light than our round pupils—and impeccable hearing; they can even hear their young calling out from inside their eggshells. Also, they have taste buds.

  • Crocodilians can swim up to 20 miles an hour; they can run up to 11 miles per hour; they can hold their breath for over an hour; and they can survive for months in between meals.

  • Crocodilians don’t chew their food; instead, they’ll swallow it whole, or if it’s too large, they’ll tear it up into large pieces. What’s more, they have to juggle their prey around so that it’s positioned in such a way that when they toss it back, it slides down their throat. 

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