More Animal Wonders
I’ve been fascinated by the diversity of life since I was a little kid. I wrote a two-part piece, “Animal Intellect” (see Archives, Mar 2013), about how they process and respond to information, and also a piece on plants, (“Plants Are People, Too,” Archives, May 2016). It seems every day we learn some astounding new things about these wonderful creatures. The reports I’m going to tell you about are discoveries made just within the last year.
For a long time, ornithologists knew that the cowbird lays her eggs in the nests of other bird species, and the birds raise the young. I don’t know why, maybe cowbirds want to party late into the night, or they’re just lazy. Now we find out the cowbird keeps an eye on her chicks from a distance, to see how they’re being raised. If they’re rejected, killed, or treated roughly, the cowbird doesn’t “use” that species anymore. I wonder, do they then pass on this information to the other cowbirds?
Frequent flier miles — We used to think the Monarch butterfly had that record, with an annual migration South of about 2500 miles. Recently, though, a 1 ½ inch long dragonfly, Pantala flavescens, makes a transatlantic journey of over 4000 miles. In addition to flight, its wings are designed for gliding on air currents. I’m a gastromorph, someone whose primary concern is food and eating, so maybe that’s why both these creatures elicited the same question in my mind: Both have high metabolisms necessary to do all that fluttering, and that takes a lot of energy, so how do they survive those distances without food?
This was one of my favorite animal stories of last year, as disco music is one of my guilty pleasures The Disco Clam, Ctenoides ales, inhabits the coral reefs of Indonesia. To ward off predators or attract food, it generates brilliant flashes of light, hence the name. But rather than using bioluminescence, generating the light itself, tiny bits of silica near the edge of the shell reflect the available light. So reflective are they the clam can even flash using the low light levels of blue, as found inside a cave. The lead researcher is Lindsey Dougherty, a doctoral candidate at the U. of California Berkeley. She says the 40 small eyes don’t have the quality of vision to be signaling or reading signals from other clams. She discovered another secret, too. The tentacles contain sulfur, using it to manufacture sulfuric acid to immobilize attackers or prey. You can see film of a large mantis shrimp wrapped around the clam, trying to open it. Then it suddenly backs off, going into a stupor. Naturally, the lyrics come to mind: “Ah, ah, ah, ah, stayin’ alive, stayin’ alive . . .”
Are some ants just plain lazy? In the July 2015 journal Behavioral Ecology and Sociobiology a study on ants was published. Dr. Anna Dornhaus of the U. of Arizona and her team examined the habits of a small brown ant, Temnothorax rugatulus, that frequents the forests of North America. Grad students briefly anesthetized each ant, then with a tiny wire gave each a specific color code. Ten colonies were observed for two weeks. Each session was five minutes, and done six times a day. 71.9% of the ants were inactive after an hour or so, and 25.1% did no work at all. Only 2.6% of the ants were constantly busy. I know what conservatives would say: That’s your socialism, feeding the lazy ones who refuse to work! Science has different ideas, though. Maybe they’re just excess workers. Less movement saves energy and food, because ants regularly regurgitate food to others who need it. They may also be older, or “retired.” They could be a military guard, as its commonplace for other ants to raid colonies for slaves. Here’s an idea: maybe they’re the poets, reciting verse or songs to inspire the workers. I’d imagine more studies are planned.
From livescience.com, 10/22/2015, we hear of a study just published in Current Biology on howler monkeys, whose booming mating calls can be heard for miles. That’s because they have a unique structure called a hyoid bone, which acts as a resonating chamber. Ten species were included in the study. Something unexpected came to light, though. There was an inverse relationship between the size of the hyoid and that of the testes. In other words, the louder the calls, the smaller the balls. This immediately made me think of the Republican presidential candidates, one in particular. My next thought was: Boy, there’s a dream job, measuring the testicles of howler monkeys. Because it costs a lot of biological energy to promote the growth of one or the other, and too much to do both, during the male’s growth and development a decision must be made over which to emphasize, balls or calls. The researchers discovered there was no relation to environmental factors, but there was to societal ones. In groups living in “harem” societies, where one male mates with several females, the males had larger hyoid bones. But in groups with multiple males and females all mating with each other, like some 60s Love-in, the males had larger testes. That doesn’t make sense to me. Shouldn’t it be the opposite? You’d think if there were a lot of males to compete with, you’d want to develop the call. Oh well, I don’t make the rules.
Not only have drones become one of the major annoyances of modern life, they’re also hazardous to navigation, and it’s only a matter of time before one collides with a plane. The Dutch police have found a creative way of dealing with the problem (from The Guardian). They’re working with Guard From Above, a raptor-training firm in The Hague. They train eagles to attack wayward drones! You can see video of a training session inside a large dirt area where you’d train horses. There’s one of those ubiquitous little quad-rotor drones buzzing along, the trainer releases this bald eagle who quickly attains attack velocity, and BAM! The eagle takes the drone to ground, wrapped in its talons. It’s a beautiful thing. And no, the irony hasn’t escaped me that the U.S. leads the world in drone manufacture, sales, and use, and one being taken down by our national symbol.
Our most recent animal wonder comes to us courtesy of sciencealert.com, this past Mar. 11th: “Scientists found a new spider in Australia that can swim and catch fish.” This bluish spider is about the size of the palm of your hand. It must have a light body, because it can float on top of the water. Have you ever seen those insects that skim across the water? We used to call them water-striders. I remember watching them as a kid, marveling at how they could float like that. I noticed that where their legs touched the water, it was slightly indented, and that’s when I first learned about the surface tension of water. The spider does this too; using its middle two pairs of legs to scuttle across the water. When disturbed or grabbing prey, it plunges through the surface and swims quickly to the bottom. Its diet consists of insects, fish, tadpoles and frogs. What I like even better is that it was named Dolomedes briangreenei, after one of my favorite scientists, Dr. Brian Greene, professor of physics and mathematics at Columbia University. You may have seen his PBS Series, “The Fabric of the Cosmos,” or read the book. He was presented with the honor at the latest World Science Foundation conference, held appropriately in Brisbane, Australia, last month. He helped to organize the WSF in 2008.
Since I have such a fascination with spiders (see “Adventures With Spiders,” Archives, Nov 2015), Let’s look at a couple more. Emmenomma joshuabelli was discovered last year. It was found that brushes and spines in the genital area generate vibrations thought to aid in mating. It was named after the famous violinist Joshua Bell. Now we guys have known for a long time about the effect of music in our mating rituals, although alcohol is usually present as well. And I’m glad they didn’t name that spider justinbieberi.
Let’s go out with a bit of acrobatics. Cebrennus rechenbergi was discovered last year in the Erb Chebbi desert of Morocco. When in danger, or just in a hurry, it can hurl itself into the air and with a combination of what look like somersaults and cartwheels, cover 2 meters per second (6.6 ft). You can go to You Tube and enter “cartwheeling spider” and watch this thing tearing across the sand. I know it’s not right to anthropomorphize animals with human characteristics, but I’d swear it looks like this guy is really having a good time. And I hope you’ve had a good time with this update on animal wonders. They really are terrific.