Postcards from the Planet

Spiders are carnivores. We all know that. But a Mexican jumping spider turns out to be an omnivore that prefers leaf tips to meat. In an article in last week’s New York Times , Jumping Spider Prefers Green Leaves to Meat, scientists explain how the spider takes advantage of the mutualistic relationship between acacia trees and ants.

Acacia trees provide shelter and food for ants by secreting a sweet nectar that the ants eat; thorns protect the trees from most herbivores and the ants sting other herbivores that approach. But this particular spider–Bagheera kiplingi–dodges the ants and eats the leaf tips of the acacia.

Bagheera is the name of a black panther–a particularly stealthy predator–in Rudyard Kipling’s Mowgli stories, part of The Jungle Book, first published in 1894. The person who first describes and names a new species of plant or animal gets to choose the name. The two people who named this spider–George and Elizabeth Peckham, who described the spider in 1896–must have liked the book!

Part of the 11-foot-long cloth woven from spider silk. Photo from AMNH.org

One of my favorite places is the American Museum of Natural History in New York City. If you’ve seen the movie “Night at the Museum” you might think you know something about the museum – but reality can be even weirder than the movies. Right now at the museum, for example, you can see an eleven foot long golden piece of cloth, made completely from (TA DA!) spider silk. Even the gorgeous golden color of the thread was supplied by the female spiders, since they are  a species from Madagascar known as the golden orb spider. The collection of the spider silk  and the weaving of the cloth was done by teams of humans. To find out more about it, check this out: One Million Spiders.

One more thing to think about – how did spiders get named Arachnids? Look for the story of Arachne in Greek mythology to find out.

Scientists  working in the Arctic have found evidence that climate changes – particularly ice coverage – are having effects on the walrus populations there. The retreat of the sea ice, and the fact that fewer ice floes are available as nurseries for walrus pups, are causing difficulties for walruses. Biologists are beginning to consider whether the Pacific walrus should be named an endangered species. This article details some of what the researchers report: Walrus .