Five Amazing Stationary Animals

As many of you know all too well, it can take effort to get up and move. You get up and move to use the bathroom, you get up and move to eat...sometimes you even have to get up and move to reproduce! While most of the animal kingdom shares your pain, there are many in the evolutionary race who have narrowly evaded the hornet's nest that is mobility. These creatures, known to science as "sessile," spend their entire adult lives firmly attached to a single place.   It should come as no surprise that all of our candidates for the most exciting sessile animals happen to dwell in the ocean, where even the most slothful creature can open its mouth and receive a steady stream of food on the water's current. On dry land, such behavior is mirrored only by the females of certain insects, which live attached to plant life under a waxy shell.

#6: Carnivorous Sea-Sponge

A flesh-eating beast you are unlikely to find in a pineapple, the surface of this innocuous-looking deep-sea organism functions as a sort of flypaper for small crustaceans, entangling their jointed limbs in a velcro-like pattern of microscopic hooks. Special cells in the sponge's body migrate around the prey to form a temporary orifice, where its lipid content is absorbed and carried to the sponge's core.    Many other sponges feed in a similar fashion, but Chondrochladia lampadiglobus, pictured here, is one of the most visually striking. Nearly all are found in the deep-sea abyss, arctic waters and underwater caves where sunlight and plankton are relatively scarce.

#4: Acorn Barnacle

I was tempted to write something about the parasitic barnacle, Sacculina, which discards 90% of its body to become an infection that castrates crabs, but I decided after much deliberation that it didn't qualify for this list because it only anchors itself to a mobile host. By contrast, acorn barnacles, the quintessential sessile animal, have little regard for what they attach to so long as they can spend at least a portion of each day submerged in water.    Related to crabs, lobsters and shrimps in the subphylum Crustacea, a barnacle begins its life as a one-eyed, swimming larva known as a Nauplius. After several molts, the Nauplius develops into a more heavily armored "Cyprid," with large antenna for seeking out others of its kind. On finding a suitable spot in the nearest barnacle encampment, it secretes an adhesive substance from the antenna and attaches itself upside-down, to spend the remainder of its life sweeping plankton into its mouth with its feathery legs.    While many sessile animals mate by releasing eggs and sperm into the surrounding water, barnacles take a more direct approach by fertilizing neighbors with an incredibly long, prehensile penis, proportionately the largest in the known animal kingdom. Unusual for a crustacean, these creatures are hermaphrodites, each individual capable of bearing young.

#3: Predatory Tunicate

Tunicates, or "sea squirts," are considered among the most unusual animals alive today. In its swimming, tadpole-like larval state, a sea squirt possesses both a rudimentary brain and a primitive "backbone" called a notochord, placing them alongside vertebrates like ourselves in the phylum Chordata. This symbol of kinship is often short-lived, however, as most sea squirts spend their larval stage, much like barnacles, looking for a permanent place to settle down, and will proceed to digest both the "brain" and "spine" as they develop into little more than a rubbery, filter-feeding bag of skin.    Though the entire group is pretty damn fascinating, the species Megalodicopia hians kicks the action up a notch with an appetite for more than just microscopic plankton. Standing like a sinister satellite dish in the abyssal current, it waits for tiny animals to blunder their way into its deceptively adorable giant mouth, closing over and digesting them in the fine tradition of the Venus fly-trap.

#2: Hydrothermal Tube-Worms

When volcanic activity deep beneath the Earth's crust forces superheated water up through the sea floor, the result is a hydrothermal vent or "black smoker;" an underwater geyser spewing clouds of boiling-hot, toxic minerals that would be instantly lethal to most of Earth's organisms. Not so for certain species of giant tube-worm, which not only thrive in this alien environment but have been known to reach nearly ten feet in length; thousands of times larger than their filter-feeding cousins in shallower, more hospitable waters. Lacking a digestive system, these worms feed through a process known as chemosynthesis, where bacteria in the animal's body feed off raw materials such as carbon monoxide, hydrogen sulfide, oxygen and methane, producing particles of organic waste that provide the worm's cells with all the energy they need.

#1: Osedax worms

As the largest single concentration of meat in the animal kingdom, the death of a whale is one of the deep sea's most celebrated events. The titanic carcass can take months or even years to completely decompose, and becomes a veritable cornucopia of new life as thousands of animals flock to the free buffet - some of which have evolved to feed on absolutely nothing else.    Stripped of most flesh by squirming hordes of hagfish and ghostly white crustacea, a fallen leviathan's monolithic skeleton soon comes alive with a tentacled bouqet of bizarre organisms known to some researchers as "zombie worms," "bone eaters" and "snot flowers". Structured more like a plant than an animal, the female Osedax worm lacks a mouth or stomach, relying on a network of "roots" to tap into its only food source, the fatty oils contained within whale bone. Like the thermal tube worms, it relies on unique symbiotic bacteria to process this nourishment.    When Osedax were first discovered as recently as 2002, biologists were perplexed by the appearance of only female reproductive organs in every mature specimen, despite the presence of male sperm and millions of fertile eggs. As it turned out, the "missing" male worms were there all along, plentiful but microscopic, living inside the bodies of the females. Continuously fertilized by her tiny inner harem, the lady snot-flower pumps thousands of eggs into the surrounding water, to drift like dandelion seeds until another colossal corpse appears on the sea floor.

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