5 questions (Mark, Philippines)


Hi guys!
My name's Mark from the Philippines. I hope you don't mind several questions that aren't necessarily related. :)

1.) I noticed most ants are either black or red. Sure there are whitish ants and some colorful Polyrachis ants but they're minorities. By black I mean dark brown to shiny black and by red I mean the many variations(reddish orange, orangeish, brown reddish etc). What's so special about the two colors? I'm guessing ants' ancestors happen to be black and red wasps and since ants don't need color change to adapt they retained their colors but what do I know. :)

2.) What's up with the way leafcutters look? Atta, Proatta, Acromyrmex etc have this thorny bodies that doesn't make sense to me. What's so special about leafcutting and fungus-growing that they need to evolve with spiked bodies? And also Polyrachis. They have this few large spikes that doesn't seem to have any significance other than birds or lizards might get pricked if they try to eat them and aesthetic purposes.

3.) I found these colony of what seems to be Crematogasters basing on their "heart-butts". They've occupied an abandoned termite nest and when I breached the walls, out came big-headed blockers. So far I haven't heard of trimorphic Crematogasters but the ones I found are, so any idea what species this might be? And also I find it weird how they have these termite style defense when others ants seem to find them distasteful. I dropped one at Pheidoles, Tetramoriums, Solenopsis, Tapinoma and Pharoah ants and they were left untouched. Even dead ones weren't scavenged. Pheidologetons might be their enemies? If so, can you tell stories about them raiding Crematogasters?

4.) I noticed these odd behavior in Pharaoh ants. A medium sized worker seems to be biting a larger worker on the neck. There wasn't any obvious signs of distress on both ants. I first guessed it was grooming but they looked totally stiff which doesn't look like grooming to me. When I disturbed them with my fingers, they appeared confused but that's obviously by the huge thing that touched them. Then they just went of with their marching nestmates. I saw 2 of these weird happening from the same colony, simultaneosly and a few inches apart. Both pairs where a median "biting" a major. Any idea what that was?

5.) I witnessed these funny grasshopper kicking garden ants. At first it was facing incoming ants and then turned around to kick them a few inches away. The ants landed exactly on another of the ants' lines which made even funnier. Is these a unique grasshopper or do many grasshoppers do these?

Thats all! Thanks!
Mark


Dear Mark,

Wow, that's a lot of questions! We'll try our best to answer them, but for most of these, we'll just be giving our best guesses, because without more information, we don't know.

1) So your first question sounds like you're asking "Why aren't ants more colorful?" But then you go on to list all the different colors that ants can be! The different shades of red, yellow, brown, and black that most ants come in are special because these are called pigment colors. They are the most common chemical-based colors in all groups of animals. Human hair, for example, is basically all the colors an ant can be. The colors ants and mammals usually aren't are the structural colors that are so flashy and beautiful in many birds, beetles, butterflies, and dragonflies (check out this website about birds for more information about the different kinds of colors animals use). The few ants that are colors that mammals usually aren't use structural colors (there are green ants and blue-ish purple-ish ants). Part of the reason ants aren't as colorful as butterflies or dragonflies is that they don't rely on visual cues for mate recognition or for sister-recognition. Instead they rely almost entirely on touch and smell. Ants aren't usually as colorful as orchid bees or velvet ants because they don't rely on aposematic, or warning coloration, to warn predators that they are dangerous. In fact, the ant body type and their habit of working together in large groups is distinctive enough that many arthropods have adapted to look like ants - they don't need to be bright orange and white to be intimidating because ants are notorious enough as it is. (see previous posts here and here on myrmecomorphy ). As you observed, ants still come in an impressive array of hues; all the pigment colors found in most other organisms are found in ants. Blues, greens, and bright whites are usually absent in ants because they don't need them for recognition, communication, or for warnings.

2) Again, you've pretty much answered your own question here. Lizards and amphibians are some of ants' most significant predators, and anything ants can do to make themselves less easy to eat would be an advantage. Something you might notice is that none of the ants that are very prickly have serious stings. There are trade-offs involved in how much energy you devote to different kinds of defenses: spines take a lot of extra nutrients to produce, just like venom. Some ants avoid predation by being fast, like members of the genera Anoplolepis and Paratrechina. Leaf-cutter ants in the genera Atta and Acromyrmex are some of the most conspicuous ants in the Neotropics. They can't run away from lizards while they're carrying those huge chunks of leaves, so they've devoted a lot of energy to being prickly and crunchy.

3) We don't know of any dimorphic Crematogaster. A genus that is often found in termitaria that is conspicuously dimorphic is Metapone. This genus is known from the Philippines, but little is known about its natural history. The observations you've made may be new to science! It's important to keep voucher collections of the ants you find and conduct behavioral experiments on, so they can be positively identified. There are more than 80 genera known from the Philippines, but this number is expected to grow with more collections. If you have pictures of these ants, send them our way, and we can try to identify them! Or at least check out the Ants of the Philippines on AntWeb, and Ants of Borneo.

Your experiments on whether or not the other ants wanted to eat your "Crematogaster" might be more meaningful if you conducted them using a delicious positive control. Perhaps the other ants had no appetite because they were afraid of you! If you offered the ants multiple kinds of food at the same time (sometimes called a cafeteria experiment ), then you'd know that at least they were in the mood to eat something.

4) How closely did you look at the Pharaoh ants? It could be that the "majors" were actually wingless reproductive females. In larger Pharaoh ant colonies, there are often multiple queens, and sometimes they assist in foraging (which is part of why they are so easily spread by humans--if a queen happens to be foraging in your lunch box when you pick it up and take it home, you've just started a new Pharaoh ant colony!). The true workers will still take it upon themselves to carry the queens around sometimes, though. We don't understand exactly why they do this, but it could be a relict from when they used to be monogynous.

5) That's really funny. Very little is known about insect behavior in the tropics. Most larger insects will try to flick ants away from themselves if they are being harassed. But wouldn't that be cool if they could flick them into another angry line of ants? If you could demonstrate this by doing statistics on how likely an ant was to be flicked by a grasshopper into another ant line vs. just anywhere, that would be a great scientific paper!

Sorry we can't give you more definite answers to many of these questions, Mark. But if people like you keep making great observations like these in different areas in the tropics, maybe someday we'll know for sure!

Best,
Jesse Czekanski-Moir, Noel Tawatao, & the AntAsk Team

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