Body Armor, Quills and Spines – Life in the Danger Zone
It appears certain animals have taken extreme measures to avoid becoming dinner. California State University, Long Beach (CSULB) assistant biology professor Ted Stankowich has developed a new theory as to why some mammals, like armadillos, porcupines and skunks, have evolved body armor, quills, spines, dermal plates or noxious sprays that help protect them from predators and others have not. His research currently appears online in the journal Evolution and will be featured in the July print edition.
Stankowich examined more than 3,500 mammal species and determined that a specific combination of body size, habitat type and diet makes for a particularly dangerous lifestyle. Mammals identified as living in this “danger zone” were most likely to have developed strong defense mechanisms.
“The ‘danger zone’ applies to medium-sized mammals living in environments with very little brush or vegetation. This risk is compounded when they also primarily eat insects, so they are frequently looking down at the ground and are less likely to see animals approaching them. This makes them easy potential prey, so natural selection should favor stronger defenses in case they are surprised by a predator,” said Stankowich. “Animals, such as porcupines, pangolins, hedgehogs and echidnas, who have this lifestyle, have evolved with body armor, quills, sprays and other defenses to protect them from predators.”
Stankowich notes that not all animals in the danger zone have evolved physical defense mechanisms.
“There are some animals that exist in the danger zone, but have evolved different behavioral ways to protect themselves from predators,” said Stankowich. “For example, rabbits and kangaroo rats hop quickly to get away, more rapidly than they could if they just ran. Small to medium-sized carnivores, like the American lynx and the red fox, can typically defend themselves with sharp teeth and claws while being aggressive. And other less defended mammals like groundhogs can escape into burrows in the ground.”
Additionally, there are some species of porcupines that have quills and are medium-sized, but do not exist in the danger zone. Rather, they live in trees or other closed habitats and are more herbivorous. Stankowich and his research team are currently studying these defended mammals more closely to understand how and why natural selection has favored the evolution of quills in a group with such diverse lifestyles.
In addition to mammal research, Stankowich teaches mammalogy, evolution, ecology and behavioral ecology classes to more than 200 students a year in CSULB’s College of Natural Sciences and Mathematics. Last month, he accepted the university’s award for “Early Academic Career Excellence”.
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About California State University, Long Beach
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