7 Impressive Animal Defense Mechanisms

NOAA Photo Library, Flickr // CC BY 2.0
NOAA Photo Library, Flickr // CC BY 2.0

The deep-sea squid known as Octopoteuthis deletron has a startling defense mechanism: When threatened, the squid attacks its predator and then pulls away, breaking off the tip of its own arm and leaving it behind as a diversion. As the arm continues to glow and twitch, the squid makes its escape.

But this squid isn't the only creature with a bizarre tactic for keeping itself alive. Here are several other animals with impressive defense mechanisms.

1. THE LIZARD THAT SHOOTS BLOOD FROM ITS EYES

The Texas Horned Lizard is a scary-looking creature. Brown, plump and perfectly camouflaged in its native sandy environment, its first line of defense is its spiky demeanor. If the sharp spikes and horns don't ward off predators, the lizard steps it up a notch and squirts a well-aimed stream of blood out of its eyes. The stream of blood, which can go as far as 5 feet, is mixed with a foul-tasting chemical that wards off predators. But this odd weapon comes at a cost: The lizard may release one-third of its total blood supply this way, amounting to 2 percent of its body mass. Unfortunately, its population numbers are dropping thanks to a threat that won't retreat after a well-aimed squirt: habitat loss due to rapid urbanization in the Lone Star State. 

2. THE HAIRY FROG THAT BREAKS ITS OWN BONES

Trichobatrachus robustus, aka hairy or horror frog

Emőke Dénes, Wikimedia Commons // CC BY-SA 4.0

What if every time you felt threatened, your first and only method of defense was to break your own bones and use them for weapons? Meet the hairy frog, a Central African species. When breeding, the male frogs develop thin strands of skin along the sides of their bodies that resemble hair. In theory, these strands also allow the frogs to take in more oxygen while they watch over their eggs. But what's really compelling about this frog is its ability to crack its own toe bones and push them through their skin to form sharp claws, which are great for warding off would-be attackers.

While it's not completely clear what happens to the bones after the threat of attack subsides, researchers believe the bones slide back under the skin when the frog's muscles relax.

3. THE NEWT THAT TURNS ITS RIBS INTO SPIKES

spanish ribbed newt

The hairy frog isn't the only amphibian that uses its bones for weapons. When attacked, the Spanish ribbed newt shifts its ribs forward at an angle and pushes them through its stretched skin. The resulting effect is a row of spikes on either side of its body. Like the hairy frog, the newt has to force the bones through its skin every time it is attacked, but the mechanism seems to cause little or no harm to the creature. Maybe one day it'll get its own robot protector: A team of researchers at the the Swiss university EPFL created a robotic salamander inspired by the newt, which they called the Pleurobot (after its scientific name, Pleurodeles waltl).

4. THE TERMITE THAT BLOWS ITSELF UP

Talk about taking one for the team. When under attack, a species of termites found in the French Guiana rain forests sends older worker bugs on suicide missions to defend the whole colony. These older bugs, no longer as useful to the pack as they once were, come equipped with "explosive backpacks" that, over a lifetime, fill with toxic crystals produced by glands in the abdomen. When mixed with salivary gland secretions, these crystals create a toxic liquid that explodes on enemies, paralyzing them and killing the worker at the same time. These termites aren't alone among insects in using a suicidal defensive tactic: When faced with a threat, an ant found in Borneo expands its abdomen until it ruptures, shooting out a toxic liquid

5. THE FISH THAT SLIMES ITS ENEMIES

Hagfish are eel-shaped marine animals with the incredibly useful ability to slime their enemies. When threatened, the hagfish emit a slime from their pores that, when mixed with water, expands into a gelatinous goo that can either trap predators or suffocate them by clogging their gills. The video above shows a hagfish being attacked 14 separate times by sharks and other big fish, and coming out completely unharmed. Each predator took one bite before immediately spitting the hagfish out and swimming away, gagging. The best time to encounter a hagfish is probably after it's emptied its slime glands withstanding such an onslaught; the glands take three to four weeks to refill.

6. THE SEA CUCUMBER THAT SHOOTS ORGANS OUT OF ITS ANUS

sea cucumber on coral reef
iStock

Sea cucumbers can seem pretty boring. There are some 1250 known species of these sedentary creatures in the world, and many of them do indeed look like cucumbers. But when it comes to survival, things get interesting. Like starfish and sea urchins, sea cucumbers are echinoderms, and they can regenerate lost body parts if necessary. This comes in handy when they're threatened. The sea cucumber will expel its internal organs, which are sticky and sometimes contain a toxic chemical that can kill predators. They don't have much of a defense against pollution though, which is a problem, because they're superstar ocean-floor cleaners.

7. THE OPOSSUM THAT PLAYS DEAD

possum playing dead in the grass
Tony Alter, Flickr // CC BY 2.0

You can't do a roundup like this without at least mentioning the opossum. We typically refer to this creature's infamous defense mechanism as "playing dead," but there's actually nothing playful about it; the act is completely involuntary. Under intense fear, opossums fall into a comatose-like state that can last for hours, long enough to convince any predator that the opossum is already dead. Also unappetizing: Fear causes these animals to emit a corpse-like smell that only adds to their act. Thank the opossum for providing some defense for us too: They eat venomous snakes and ticks, gobbling up to 4000 insects a week.

Scientists Find Fossil of 150-Million-Year-Old Flesh-Eating Fish—Plus a Few of Its Prey

M. Ebert and T. Nohl
M. Ebert and T. Nohl

A fossil of an unusual piranha-like fish from the Late Jurassic period has been unearthed by scientists in southern Germany, Australian news outlet the ABC reports. Even more remarkable than the fossil’s age—150 million years old—is the fact that the limestone deposit also contains some of the fish’s victims.

Fish with chunks missing from their fins were found near the predator fish, which has been named Piranhamesodon pinnatomus. Aside from the predator’s razor-sharp teeth, though, it doesn’t look like your usual flesh-eating fish. It belonged to an extinct order of bony fish that lived at the time of the dinosaurs, and until now, scientists didn’t realize there was a species of bony fish that tore into its prey in such a way. This makes it the first flesh-eating bony fish on record, long predating the piranha. 

“Fish as we know them, bony fishes, just did not bite flesh of other fishes at that time,” Dr. Martina Kölbl-Ebert, the paleontologist who found the fish with her husband, Martin Ebert, said in a statement. “Sharks have been able to bite out chunks of flesh, but throughout history bony fishes have either fed on invertebrates or largely swallowed their prey whole. Biting chunks of flesh or fins was something that came much later."

Kölbl-Ebert, the director of the Jura Museum in Eichstätt, Germany, says she was stunned to see the bony fish’s sharp teeth, comparing it to “finding a sheep with a snarl like a wolf.” This cunning disguise made the fish a fearful predator, and scientists believe the fish may have “exploited aggressive mimicry” to ambush unsuspecting fish.

The fossil was discovered in 2016 in southern Germany, but the find has only recently been described in the journal Current Biology. It was found at a quarry where other fossils, like those of the Archaeopteryx dinosaur, have been unearthed in the past.

[h/t the ABC]

These Are America's 50 Most Rat-Infested Cities

iStock.com/Pierre Aden
iStock.com/Pierre Aden

New York City, home to the subway pizza rat, is surprisingly not America’s most rodent-infested city. That dubious honor goes to Chicago, according to a new analysis spotted by Thrillist.

A breakdown of the “50 Rattiest Cities” in the U.S. has been compiled by Orkin, a pest control service with locations across the country. The company tallied up the number of commercial and residential rodent treatments it carried out in each city over a period of 12 months (September 15, 2017 to September 15, 2018) and then ranked them. While the evidence is anecdotal, as it comes from just one company, it does reveal the areas where rat exterminators are in high demand.

This is the fourth year in a row that Chicago has been named the country’s rattiest city. Orkin isn’t the first to notice the city’s rodent problem, either. In July, Chicago was reportedly dubbed the “rat capital of the U.S.” by apartment search service RentHop. It reportedly received more rat complaints than any other city last year—nearly 51,000 total. According to RentHop’s analysis, New York City came in second place, followed by Washington, D.C. and Boston.

That isn’t too far off from Orkin’s latest analysis. New York comes in at third place, just after Los Angeles, and Washington, D.C. is fourth. The biggest boom in rat populations was seen in Portland, Maine, which jumped 19 spots from last year. Chance Strandell, residential service manager for Maine Pest Solutions, told New England Cable News that milder winters may be extending the rats’ breeding period. However, it’s unclear why rats seem to be multiplying in Maine in particular.

One pregnant rat can birth up to 12 babies in a single litter, and those pups can begin reproducing at just two months old. “So after a year, a busy pair of rat parents can have 15,000 descendants,” reports KATU in Portland, Oregon (number 24 on Orkin’s list).

Charleston, West Virginia, has also been teeming with rodents, having risen 17 spots from last year. Check out the full list of the 50 most rat-ridden cities below—and if you have musophobia (a fear of rats or mice), you may want to plot your move to one of the cities toward the bottom of the list.

1. Chicago, Illinois
2. Los Angeles, California
3. New York, New York
4. Washington, DC
5. San Francisco, California
6. Detroit, Michigan
7. Philadelphia, Pennsylvania
8. Cleveland, Ohio
9. Baltimore, Maryland
10. Denver, Colorado
11. Minneapolis-St. Paul, Minnesota
12. Dallas-Fort Worth, Texas
13. Boston, Massachusetts
14. Seattle, Washington
15. Atlanta, Georgia
16. Indianapolis, Indiana
17. Miami-Fort Lauderdale, Florida
18. Hartford, Connecticut
19. Pittsburgh, Pennsylvania
20. Cincinnati, Ohio
21. Milwaukee, Wisconsin
22. Charlotte, North Carolina
23. Houston, Texas
24. Portland, Oregon
25. Columbus, Ohio
26. San Diego, California
27. Raleigh-Durham, North Carolina
28. Buffalo, New York
29. New Orleans, Louisiana
30. Norfolk, Virginia
31. Richmond, Virginia
32. Albany, New York
33. Kansas City, Missouri
34. Portland, Maine
35. Nashville, Tennessee
36. St. Louis, Missouri
37. Sacramento, California
38. Greenville, South Carolina
39. Grand Rapids, Michigan
40. Phoenix, Arizona
41. Orlando, Florida
42. Tampa, Florida
43. Burlington, New York
44. Champaign, Illinois
45. Rochester, New York
46. Syracuse, New York
47. Charleston, West Virginia
48. Dayton, Ohio
49. Memphis, Tennessee
50. Flint, Michigan

[h/t Thrillist]

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