Though 2018 has come and gone, it isn’t too late to relish some interesting findings about animals and math from last year. Here are some highlights.
To find food, even worms do complicated calculations
That’s according to a Nature Communications study published in August 2018. In a news release, study author Alon Zaslaver, a neurogeneticist at Hebrew University of Jerusalem compared the food-finding tactic used by worms and other animals to the game “Hot or Cold?”
“Imagine you’re in a huge dark house and a chocolate cake has just been taken out of the oven. To find the cake, you’ll probably sniff around to see what direction the cake scent is coming from and begin walking in that direction,” he said.
C. elegans (nematodes) for instance, follow a similar process, with some modifications. When their neural cells sense the smell of food, they begin traveling on a path towards the scent. If the intensity of the scent keeps increasing, they continue on this path. However, if it decreases, the worms’ neural cells instruct them to stop and seek a different route.
The worms re-route towards their yummy targets with the help of a second neural cell which calculates whether the odor intensity is positive (getting warmer) or negative (getting colder). In short, “This second cell senses ‘derivatives,'” the news release states, adding “If the cell detects a negative derivative, it understands that it’s getting further from the chocolate cake and needs to recalculate its route. This cell constantly computes new scent data to detect whether the current odor intensity is getting stronger or weaker and charts a path based on these new differential measurements. With a negative reading, the second cell will tell the worm to chart a new path whereas a positive one will tell it to stay the course.”
Why can non-human animals broadcast more of their vocal power?
Some animals can holler in ways that humans can’t replicate, according to a news release. Humans are able to broadcast about 1% of their vocal power, a paltry amount considering that some animals have the ability to broadcast all of theirs. Some of this discrepancy can be explained by the ways these animals open their mouths extremely widely or use their body shapes to direct sound, sound broadcasting advantages that humans can’t replicate with their own bodies.
Another key factor? Radiation efficiency, or the amount of sound produced that is actually transmitted out of an animal’s mouth. Sound power can get lost at different stages of sound production, reducing radiation efficiency.
In a May 2018 study published in the Journal of the Acoustical Society of America, Ingo Titze, director of the National Center for Voice and Speech at the University of Utah, and Anil Palaparthi, research scientist at the same center, developed a formula for radiation efficiency and quantified the factors that impact it.
“Some birds and mammals smaller than a volleyball can shout as loud as a human – largely because of high radiation efficiency,” the news release notes, adding “In calculating the factors that play into radiation efficiency, Titze and Palaparthi found that animals have three major characteristics that improve their efficiency: wide mouths, high frequencies and the ability to turn their entire body into an acoustical reflecting chamber.”
The tipping point that propels spiders from cooperation to attack
Anelosimus studiosus spiders are subsocial arachnids. Sometimes they live in colonies, spinning their webs, laying their eggs and sharing their prey, according to a news release. The alternative? They attack each other.
The cause of the peaceful conditions? Relatively cool environmental temperatures. If temperatures climb to 31°C, spider infighting ensues, according to a September 2018 paper published in the Proceedings of the Royal Society B: Biological Sciences.
“Like many dynamic, complex systems, these colonies of social spiders have a tipping point where some small environmental perturbation can cause an abrupt and dramatic shift – a bifurcation – in the behavior of the system,” the news release notes.
Yet, reversing the heat-related agitation in these spiders isn’t as simple as cooling their environment back below 31°C. ”When the temperature cools, [spider] colonies do not immediately return to their calm state upon reaching the critical 30–31°C, but require much cooler temperatures (less than 27–28°C) to return to their prior state. Thus, at an equivalent temperature, say 29°C, a colony can be characterized by high levels of infighting or calm cooperation, depending on its history,” according to the research paper.
“‘Conservation biology tends to hint that if we return to a previous set of environmental conditions, living systems that were disrupted by an environmental change will recover to their former state,’ says Jonathan Pruitt, Canada 150 Research Chair at McMaster University and lead author on the paper. ‘It turns out, you may have to rewind the system to a much earlier set of environmental conditions to drive its recovery,'” the news release states.