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Poison Dart Frogs: Highly Toxic, but Devoted Parents

Phyllobates terribilis, the golden poison dart frog. Photo Credit Wilfried Berns

Poison dart frogs, the family Dendrobatidae, come in an amazing array of colours, so it shouldn’t be surprising that they also rank amongst the most toxic creatures on earth. The golden poison dart frog (pictured above) carries enough venom to kill ten grown men, but only measure 5cm (2 inches) in length. It is this venom that lead to their common name. The Indigenous Emberá people of Colombia used to tip their blowgun darts with this venom.

While they may be incredibly toxic, they can also be very caring parents. Females of some species, such as those of the genus Oophaga,  have been known to go to rather extensive measures to care for their young. The mother will lay her eggs in a small pool of water, where they will be fertilized by the father. Once they’ve hatched, she will carry her tadpoles one by one up to pools of water that have collected in plants high up in the trees. Each plant will only carry one or two tadpoles, so she must spread her young amongst several homes. She must then visit each plant on an almost daily basis to lay unfertilized eggs for her tadpoles to feed on. When they have matured into fully fledged poison dart frogs, they will leave their homes and carry on with their own lives.

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Alopias pelagicus: The Thresher Shark’s Tail-Whip

Alopias pelagicus swims along:

Photo Credit: WIKIMEDIA, Petter Lindgren

The extraordinary caudal fin (or tail) of Alopias pelagicus, a thresher shark, makes up about half of their total length. It is therefore not surprising that it plays an important role in the lives of thresher sharks. These sharks are able to use their impressive thresher like caudal fin as a weapon when hunting sardines.

A common defense strategy of schooling fish, such as sardines, is to form what is known as a bait ball. By forming a large clump like this, the fish on the inside remain protected (each fish takes a turn on the outside), and predators may become confused. To counter this, the thresher shark will use its amazing tail as a whip. This sort of tail-slap is strong enough stun or even kill enough pray for the shark to eat. Just as a normal bullwhip, the tail winds up, strikes, then returns, hopefully carrying some stunned pray with it. While this has long been a suspected behaviour of these sharks, it is only recently that it has been observed in the wild.

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The Comb Jellies: Complex Evolution

A comb jelly repairs itself:

Photo Credit:  NOAA Photo Gallery/ Photo by Kevin Raskoff

While superficially similar to jellyfish, the comb jellies make up a different phylum altogether (phylum Ctenophora). Their name comes from the cilia that run in rows along their bodies. The beating of the cilia will propel the jellies forward through the water. In the dark, they can be seen by the pulsing lights that run up their body. While this can be a spectacular display, it is not their most extraordinary feature. What has been mystifying scientists is their nerve system.

Unlike the simple nerve net of jellyfish, the comb jellies have a rudimentary brain and synapses. They also possess a middle tissue layer that ultimately forms muscles. While this makes them seem quite sophisticated, their genome seems to show that they are quite primitive, possibly even evolving before sponges. This has baffled biologists as it would seem that either the comb jellies evolved such a complex system independently from the rest of the animal kingdom, or that they share a common, complex ancestor, whose traits were then lost in the sponges and jellyfish, later to be evolved again. Either of these possibilities greatly shifts our current understanding of the origin of multicellular life and could vastly change our depiction of the evolutionary tree of life.

Scientists hope to examine comb jelly’s genome further, as it is still unclear how they manage to operate their various body parts. In addition, they also possess regenerative capabilities. It is hoped that by gaining a better understanding of how the comb jelly repairs its muscle and nerve tissue, this concept can be applied to human tissues as well.

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The Complex Lives of Prairie Dogs

A prairie dog listens from his burrow:

Photo Credit: Aaron Siirila

Well known for their burrows, prairie dogs are a common sight in the American open grasslands and prairies. While farmers and homeowners may not appreciate their destructive structures, the burrows of prairie dogs are quite complex. A single family’s burrow will contain different compartments, each with its own function, such as a nursery, a sleeping area, listening holes, and even toilets. One species, the Black-tailed prairie dogs, will congregate in towns, usually spanning approximately half a square mile (1.3 square kms). The largest town recorded was in Texas and spanned 25 000 square miles (65 000 square kms) and may have homed up to 400 million prairie dogs.

While their living arrangements are quite complex, scientists have recently shown that they also use a complex communication system. By recording the warning calls of prairie dogs in different situations, scientists have shown that they not only warn their peers of approaching danger, they also describe it in quite a high amount of detail. They are able to not only describe the approaching species, but also describe its physical characteristics, such as colour, size, or behaviour. It is hoped that this breakthrough will lead the way to animal-human translating systems within 10 years

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Sea Monkeys: Brine Shrimp

This is a sea monkey:

Photo Credit: FLICKR, djpmapleferryman

So what exactly are sea monkeys? Sea monkeys are actually brine shrimp. Brine shrimp live in salt lakes. They can handle such extremely salty conditions, that some lakes will only be inhabited by brine shrimp and the algae they feed on. So how can brine shrimp be packaged and sold as sea monkeys?

The powder that comes in the package is actually their eggs. The eggs that brine shrimp lay are called cysts, and are encapsulated. This means that they are protected and can remain dormant for incredibly long periods of time, much like how plant seeds can be kept until it is time to plant them. When they are placed in salt water, the eggs sense that they are in the right environment, and hatch. They develop quickly, reaching maturity in about eight days, and can reach a final length of 15 mm (half an inch).

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The Dromedary Camel: Master of the Desert

The Dromedary Camel:

Photo Credit: Jjron

Camels are well known for their humps, with different species having one or two. The Dromedary camel possesses a singular hump, which is part of what allows it to survive in the harsh desert conditions. Made of mostly fat, dromedaries can break down the contents of their hump into water or nutrients, allowing it to travel vast distances without water. While their hump is the most famous of their adaptations, it is not the only one.

Dromedaries are also capable of closing their nostrils, keeping the sand from getting into their windpipes. Their large, padded hooves allow them to spread out their weight on top of the sand, preventing them from sinking into the dunes. Like humans, they have eyebrows and eyelashes, but theirs are much longer and bushier to keep the sand out.

Dromedaries are greatly valued as pack animals, and today, nearly all of the world’s camels are domesticated.

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Fireflies (lightning bugs)

An unknown species of firefly:

Photo Credit: Emmanuelm at en.wikipedia

Also known as lightning bugs, fireflies are well known for the blinking light they emit at night. Members of the family Lampyridae, they are species of beetles that take in oxygen and combine it with luciferin to create their distinctive glow in their abdomen.

The glow serves multiple purposes. It can be a signal to predators that they are unappetizing and should be avoided, but is also a message to the other members of their own species. There are about 2000 species of fireflies, each with it’s own unique light pattern. This helps them find each other during mating season. Some females, however, will imitate the light pattern of another species so that when an unsuspecting male comes to investigate, she can eat the poor fellow.

The California Condor: Masters of the Skies

Two preening Condors:

Photo Credit: William H. Majoros

The California Condor (Gymnogyps californianus) is probably best known for the efforts surrounding their preservation. In the late 1970s, the California Condor’s population had dropped down to just a few dozen individuals. By 1987,  there were only 10 of these birds left. It was at this point that scientists captured them for a captive breeding program.

Condors reproduce very slowly, only laying one egg every two years, but if their egg is stolen, they will lay a second or third. Scientists took advantage of this by stealing the eggs laid by the females and raising them in captivity.

Condors are the largest birds in North America, with wing spans reaching up to 3 meters (10 feet), but are still severely endangered. There are now over 200 birds in the wild, a big improvement from 1987, and preservation efforts still continue. Hopefully, their population will continue to increase, and may some day reach the levels it once was.

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The Alligator Snapping Turtle and their Natural Lure

This is the alligator snapping turtle:

Photo credit: Gary M. Stolz/U.S. Fish and Wildlife Service

The alligator snapping turtle (Macrochelys temminckii) is amongst the largest turtles in the world, weighing up to 100kg (220lbs) and reaching a length of 66cm (26 inches). They live in freshwater, and hunt by lurking at the bottom of the river or lake with its mouth open. A special patch of skin on the tongue is coloured bright red, and almost looks like a worm. This lure will attract fish to come down and investigate, so that the turtle can snatch them up.

They are often considered to appear prehistoric, due to their spiky shells and sharp beaks. Unfortunately, this makes them a target for hunters who wish to sell them in the exotic animal trade (although they live almost exclusively in the southeastern United States), or sell their shells as novelties.

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Cicadas: The Sound of Summer

This is a cicada up close:

Photo Credit: Martin Hauser

On hot summer days, one can often hear the calling song of the cicada on the wind. While their call is an iconic sound of summer, cicadas are amongst the loudest insects known to man. Humans start to feel pain by sounds in the range of 110 to 120 decibels, with the sound of a rock concert falling comfortably within this range at 115 decibels. A swarm of cicadas can top out the rockers, reaching a level of 120 decibels. While similar to locusts, they are not in fact the same plague of insects.

Another iconic trait of the cicada is their life cycle. Cicadas will remain underground for 13 or 17 years until they finally emerge all at once in a swarm. It’s not quite certain why they remain dormant for so long (or why they allow the years to pass in prime numbers), but there are a few theories. Firstly, it is thought that perhaps by swarming out all at once, there will be so many cicadas that predators can have their fill, leaving enough insects to mate and allow the species to continue. Another theory is that it is a behaviour held over from their evolutionary history, when the world was cooler. Living underground would hopefully protect them from unexpected cold snaps.

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