# data[].attributes.headline
Why Birds Can Sleep on Branches and Not Fall Off

# data[].attributes.subject
Why Birds Can Sleep on Branches and Not Fall Off

# data[].attributes.body
Their talons work through a series of pulleys made of tendons, as these GIFs and drawing explain.

By Alexis C. Madrigal

# data[].attributes.attachment_link.readable_text
You ever see a bird clutching onto a branch high in a tree and wonder, "What happens if it falls asleep? How could it hold on?"

The avian talon works through a "pulley system of tendons," according to the animal morphology blog Ars Anatomica, and it can lock into place.

"The bird's foot closes and grasps automatically as the ankle and knee joints are bent," we read. "This grasp cannot be released until the limb is straightened again."

So, instead of expending precious energy holding the muscles tight-as you would if you were hanging onto a branch with your fists/arms-the system simply physically locks in place.

A 1990 paper in Zoomorphology goes into more depth about the biomechanics of the lock, which results from the placement of the tendons and evolved specializations of their texture.

And, of course, this wondrous anatomical system doesn't just come in handy on telephone wires, but also during attacks:

Raptors swoop down on prey with talons/legs outstretched. The impact with the prey folds the raptor's legs against its body, causing the talons to clench automatically, tearing into the prey. The automatic grip is strong enough to kill, and is what allows many hawk species to catch and kill other birds in midair.

UPDATE: It appears that this mechanism - as described in the paper and post above - is an area of active scientific dispute (!). A 2010 paper in the Journal of Experimental Zoology Part A found that such a mechanism did not exist in the European starling. Thanks for the update, Ed Yong.

Ars Anatomica

Via Deb Chachra

# data[].attributes.attachment_link.title
Why Birds Can Sleep on Branches and Not Fall Off

# data[].attributes.attachment_link.description
Their talons work through a series of pulleys made of tendons, as these GIFs and drawing explain.

# data[].attributes.attachment_link.readable_text
TRAP TYPE: Snap Trap
One species, Dionaea muscipula J.Ellis (1768), occupying habitats in the southeastern United States of America (North Carolina, South Carolina).

The steel trap of Dionaea is hardly as powerful as the ones set by trappers for wolves, beavers or bears, but it is just as effective at catching its own small prey. Figure 1 shows the traps ready to spring. Its growth in the wild is restricted to the bogs in the central southeastern coastal plain of the United States. Figure 2 below is a Venus flytrap in its natural environment.

Near the crease where the two leaf "jaws" join there is a series of tiny hairs. If an unwary insect walks across these hairs, touching two or more of them in succession, the leaf will close quickly enough to prevent its escape. Unable to escape between the hair-like teeth at the edge of the leaf (Figure 3), the helpless insect is slowly digested and absorbed by the leaf. Glands on the leaf surface secrete several digestive enzymes that help to decompose the insect. Once the insect has been digested sufficiently, the leaf re-opens for another victim.

The sensitive hairs at the fold of the leaf prevent the leaf from closing every time a drop of rain lands on it, because the leaf requires that two or more of these hairs be triggered in succession (Figure 3). If the leaf does close without a victim, it will re-open in a few hours. According to Lloyd (in George 1962), the traps can only catch about three victims before the leaves turn black and die. And even if the trap fails to catch anything, like when you tease it by touching a hair with a small brush, it can only reopen and close again about seven times! So, don't tease the flytrap!

The mechanism of closing has fascinated biologists for many years. How can an inanimate plant react so quickly to the stimulus of touch? The most widely accepted explanation had been that a rapid change in the turgidity of the cells occurs. That is, there must be a sudden change in the water pressure in the cells - the cells of the bottom part of the midrib, that is. Now we know that it is not nearly so simple, nor is our old explanation valid, although the lower midrib cells do indeed take in more water. In Dionaea, the closing occurs in as little as a half second. Salisbury and Ross (1985) explain the phenomenon as acid growth.

Early theories on the acid growth suggested that potassium or sodium must rush into the lower midrib cells to create an osmotic gradient. That means there is more salt inside than outside the midrib cells, and more water outside those cells than inside. However, Hodick and Sievers (1989) provided evidence that a change in turgor pressure due to movement of potassium or sodium was not the cause, but they were unable to provide any evidence to support an alternative theory.

First, it appears that when you touch the hairs on the leaf, it causes a change in the electrical potential of the leaf. That sends a signal to the midrib somewhat like the signal your body sends when you wiggle a hair on your arm. Your brain knows you have been touched. In this case, the midrib "knows" that the leaf has been touched. But the mechanical process that follows this impulse was elusive because any attempts to study it resulted in the leaf closing, thus making it impossible to study the osmotic condition of cells of the open leaf.

Nevertheless, we now we have a somewhat clearer picture, but it still is only a collection of circumstantial evidence without direct links to demonstrate cause and effect. First the hairs are triggered, two in succession, and these triggers set up a change in the electrical potential, sending a signal to the lower cells of the midrib. Then a flurry of things happen so fast that we don't know what happens first. The growth hormone IAA appears in the midrib in increased concentrations. Hydrogen ions move rapidly into the cell walls of the midrib in response to action potentials from the trigger hairs ( Salisbury and Ross (1985)).

We can only guess what happens here, but a good guess would be that a proton (H⁺) pump moves H⁺ ions out of the midrib cells and into the cell wall spaces between the cells. (Cell walls are really lots of fibers hooked together, creating a network of small capillary spaces.) Hydrogen ions naturally make this area more acid. These hydrogen ions seemingly loosen the cell walls, probably by dissolving the calcium pectate that glues the cellulose together, causing the tissues of the lower side of the midrib to be come flaccid. Calcium (not potassium or sodium as thought earlier) increases inside the cells and the cells absorb water.

It seems reasonable that this calcium might move into the cells by following the charge gradient. After all, if H+ ions left, the cell now has negative charges (electrons) that have no positive partner; the cell has a negative charge. This negative charge will attract positively charged things (positive ions, or cations) from outside the cell, like the Ca⁺⁺ (calcium ions) that were freed from the calcium pectate bonds of the cellulose fibers. Once the calcium enters the cell, it creates an osmotic gradient. There is now a greater proportion of Ca⁺⁺ and smaller proportion of water (H ₂O) on the inside of the cells than on the outside of the cells in the cell wall spaces. The result? Water enters the cells by osmosis. Since the cells have become unglued, they are able to expand as they take in water, and hence they grow.

This results in the expansion of the outside of the leaf and the "springing" of the trap. Yes, all this happens at lightning fast speed to make the leaf close. The cells remain at this larger size and the cellulose eventually increases to strengthen the walls. That gets the trap closed, but in a few days, it must re-open. Once the insect is digested, the cells on the upper surface of the midrib will grow, much more slowly, and the leaf will re-open.

As you might imagine, the leaf cannot keep doing this rapid growth trick forever. That is why it is only able to close its trap about seven times during the life of a leaf. But why does it do this at all? In its boggy peatmoss habitat, nutrients are very limited. It can't use the nitrogen in the atmosphere (neither can we!), but it does need some form of nitrogen. Experiments on the Venus flytrap by Roberts and Oosting (1958) suggest that perhaps it is the organic form of nitrogen and phosphorus that is important to the insectivorous plants. And the trapped insects give them just that.

Growing your own Venus Flytrap

The Venus Flytrap is one of the easiest carnivorous plants to grow. If you wish to grow one or more, they have only a few requirements such as, wet roots, high humidity, full sunlight, and poor, acidic soil. It comes shipped to you as a bulb or rhizome. Plant it root side down so that the top of the bulb is even with the soil. A recommended soil mixture is one that contains sphagnum moss and sand. Do not add fertilizer or lime. Your plants will do better if you transplant them into new soil every few years.

In order to provide high humidity for your Venus Flytrap, plant it in a terrarium or in a glass container with a small opening. An old aquarium or fish bowl makes a good container for this purpose. You need to watch your terrarium in the summer because the temperature inside the glass may get too hot. Two hours in the sun may be sufficient. If your plants wilt, then they need to come out of the sun sooner. Just the opposite is true for winter. If it gets very cold in your area you may need to move your plants away from the window or cover them at night in order to keep them warm and moist. However, your Venus' Flytrap will experience a dormant period in the winter, from Thanksgiving to Valentine's Day so it needs fewer hours of daylight and cooler temperatures.

Another way is to plant it in a pot and place the pot in a larger container such as a bucket. Partially cover the top of the bucket with a piece of glass or Plexiglas. Don't cover the entire top because air needs to circulate.

After your plant matures, it may produce flowers on a tall stalk far above the leaves. It has to be high above the leaves so insects pollinating the flowers do not get trapped in the leaves. Each flower produces very tiny seeds. They are about the size of the period at the end of this sentence. Plant the seeds right away or store them in the refrigerator. If you pinch the flowers off, the leaves will grow more vigorously since growing flowers takes a lot of energy from the plant.

The Venus' Flytrap also reproduces via its rhizome. It never has more than seven leaves. If your plant has more then seven leaves, it has already split off another plant from the mother plant. You may want to try pulling a leaf off and replanting it. Eventually, this leaf will die off and a tiny, tiny new plant will emerge.

If you wish to obtain and grow Venus' Flytraps you may check to see if you have a local greenhouse that carries them.

If you grow your plant outside, it will get enough insects to eat. If it rains the container may fill up with water but this will not hurt the plants, they can live underwater for months. If you grow your plant inside you will need to feed it insects. A couple of houseflies or small slugs per month is enough during the growing season. Do your plant a favor and DO NOT feed your Venus flytrap plants hamburger! Indigestion and rot may occur and usually your plant will die. Find a "just right" sized bug instead!

American Journal of Botany abstracts for research papers about Dionaea.

The Mechanism of Movement and the Duration of the Effect of Stimulation in the Leaves of Dionaea, William H. Brown - Volume 3, Issue 2, Pages 68-90, February, 1916

The Fine Structure of the Trigger Hair in Venus's Flytrap, Mary E. Williams, Hugh N. Mozingo - Volume 58, Issue 6, Pages 532-539, July, 1971

INSECTIVOROUS (CARNIVOROUS) PLANT REFERENCES
1. George, J. 1962. Plants that eat insects. Readers Digest Feb: 221-226.
2. Hodick, D. and Sievers, A. On the mechanism of trap closure of Venus flytrap ( Dionaea muscipula Ellis). Planta 179: 32-42.
3. Salisbury, F. B. and Ross, C. W. 1985. Plant Physiology. Wadsworth Publ. Co., Belmont, Ca. 540 Pp.
4. Roberts, P. R. and Oosting, H. J. 1958. Responses of Venus fly trap ( Dionaea muscipula) to factors involved in its endemism. Ecol. Monogr. 28: 193-218.

# data[].attributes.attachment_link.description
TRAP TYPE: Snap Trap One species, Dionaea muscipula J.Ellis (1768), occupying habitats in the southeastern United States of America (North Carolina, South Carolina). The steel trap of Dionaea is hardly as powerful as the ones set by trappers for wolves, beavers or bears, but it is just as effective at catching its own small prey.

# data[].attributes.headline
Biomimetic Venus Flytrap Structures Using Smart Composites: A Review

# data[].attributes.subject
Biomimetic Venus Flytrap Structures Using Smart Composites: A Review

# data[].attributes.body
Bing Wang 1,2,Yi Hou 1,2,Shuncong Zhong 2,*,Juncheng Zhu 1,2 andChenglong Guan ²

# data[].attributes.body
Video: Encyclopædia Britannica, Inc.

# data[].attributes.attachment_link.description
Videos and Images for Venus flytrap (plant)

# data[].attributes.attachment_link.readable_text
Odontomachus, otherwise known as trap-jaw ants, belong to the carnivorous variety of ants, and you find them in subtropical and tropical regions all over the world. The general name for this variety of ants is trap-jaw ants in the Odontomachus species. They have a pair of big and straight mandibles that can open as wide as 180 degrees. There is an internal mechanism that locks the jaws in position. When the sensory hairs located on the interior of the mandible are touched, they sense the prey or object and abruptly shut on them. The ant got its name from these strong and fast mandibles. The prey is either maimed or killed by the mandibles, permitting the ants to take it back to their nest. It is possible for the Odontomachus to once again snap and lock its jaw in case a single bite is insufficient, or for cutting bigger size prey into bits. Besides, they are able to perform slow and smooth movements of their mandibles for building nests and nurturing the larvae.

These varieties of Trap-jaw ants are vigorous hunters and their stings are poisonous. Their jaws are strong enough to launch them in the air. Research conducted recently indicates that they are moving into new territory in the southeastern United States. Habitat and Distribution of Odontomachus in General

This variety of Odontomachus is seen in South to Central America, tropical regions of Asia, Africa and Australia. When we go back to 1956, there are records of Odontomachus Haematodus reported in Alabama. Of late, it is confirmed officially by researchers' that this variety has moved across the coast of the Gulf, up to Pensacola in Florida. Earlier it was assumed that "Odontomachus Ruginodus" was established in the Orlando region, but you now see it in over a hundred miles to the north of Orlando, in Florida, and Gainesville. Despite this, Odontomachus is seen only in the shrub habitats of Central Florida's very old sand ridges that are on the verge of extinction.

The whereabouts of one among the famous Trap-Jaw Ants belonging to the Odontomachus group is given below:

Here are the details about one of the well known Trap-Jaw Ants of the species Odontomachus

Odontomachus Bauri

Odontomachus Bauri Trap-Jaw Ant - Photo by: April Nobile, AntWeb.org

Odontomachus Bauri is a variety of Ponerinae Ants called Trap-Jaw ants. The trap-jaw has mandibles with a spring-loaded catch mechanism.

This mechanism enables the ant to store energy prior to releasing or striking its mandibles swiftly. O. Bauri is famous for its strong mandibles that open to an angle of 180 degrees, and that too in 10 ms of stimulation, closing in a short interval of 0.5 ms, facilitating them to trap their prey. With these mandibles, it is possible for the ant to either squeeze the prey to death or paralyze them.

The mandibles of the O. Bauri provide the ant with an amazing additional advantage in addition to its already existing gross killing power. The mandibles develop sufficient force to help these ants to cover commendable distances.

These ants are capable of launching themselves horizontally to a distance of almost 16 inches(a distance of nearly 20 times its body length), achieving unimaginable heights of upto nearly 4 inches. In actual terms, when you compare in human terms, it is the equivalent of a man of five and a half feet jumping a distance of nearly 135 feet in the air at a height of about 45 feet. This facility stands them in good stead especially when they want to escape from predators, when they just strike their mandibles on the ground, and off they catapult into the air. Howecer, an interesting factor is its inability to control its trajectory.

O. Bauri and Anochetus are of the same genus belonging to a single family called Formicidae. You can see them in the southern regions of Costa Rica, all over the tropical regions of the continent of South America, the Galapagos Islands and West Indies (other than Bahamas and Cuba).

The main characteristic of the O. Bauri is its deep brown color. In addition, it is striated at the face close to the margin of the Vertex. The length of its head is 2.09 to 3.12 mm (0.082 to 0.123 in). On its primary Gastral Tergum, you will find partially erect and comparatively symmetrical hairs. In the side view, the petiole node is dome-shaped.

The O. Bauri particularly build their nests in humid and soft grounds where they are shielded from the direct effect of sunlight, and also in locations that natural phenomena like the wind and the rain do not affect. You can find their nests below trunks of fallen trees, branches and rocks, in residues of vegetation and containers of plants.

The structure of O. Bauri's nest is polydomous, comprising of many nests in a solitary colony. This phenomenon was ascertained when it was observed by researchers that there was unity among several adjacent nests, but the aggression was rife in those nests that were at a distance of over 10 m (33 ft) from each other. In addition, it was noticed that most of the time, Trap-Jaw Ants shared food with neighboring nests.

The nests of the O. Bauri are generally small, approximately accommodating 200 ants. The areas for foraging are specific between every nest family. It is understood that O. Bauri stick to their own areas during foraging, to avoid the hassles of entering the foraging areas of its neighbor.

High Speed Mandibles

Trap Jaw Ants: Diagram by: William Creighton

In the kingdom of animals, O. Bauri are the quickest in hanging on to, killing and feeding on other insects. When one among the four triggered hairs gets stimulated, the appendage will react to the situation in 10 ms, its speed being 126 to 230 km/h. (78 to 143mph) and its jaw opens and closes at a speed of 130 microseconds on an average, that is 2300 times faster than an eye-blink? The greatest force that it applies to its jaws is about 300 times its body weight. It was also noticed that the ants used their jaws to either throw themselves backwards in order to escape or as a catapult to throw out intruders.

The biology attached to this astonishing capability is that on the stimulation of a single trigger hair, all the four motor neurons start functioning. These big motor neurons are totally concealed in a glial case, comprising of a gathering of peculiar cells, which gives nourishment and support to the neurons. A glial casing is of prime importance for delivering signals at a high speed, since it allows a smooth flow of signals, not necessitating the signals travelling from neuron to neuron.

Two big sensory neurons protrude via the nerves of the sensory mandibular right into the suboesophageal ganglion, they stimulate and control the mandibles. The mandible muscles are operated by the ends of the sensory neurons leading to the stout dendritic trunks which controls the mandibles by their stimulation.

The O.bauri's mandibles are retained in its place by means of a latch, named clypeus. On release of the latch, the whole energy that is stored is instantaneously discharged closing the mandibles, quite similar to the crossbow after firing.

The trigger muscles that we see in the O.bauri are even seen in the fastest of the synchronous muscles in the cicades. It appears that the muscles are shaped so as to contract fast. This accounts for the length of the sarcomere, which is the primary unit of the structure of the muscle.

The Trap Haw Ant prefers for its food, other insects like grasshoppers as well as human leftovers of sweet foods lying in the open. An interesting fact about these ants is that, when it exercises its super fast mandibles to strike its prey, the jaw strikes the victim and cripples it, but the ant cannot fully control its roll and lands across and away from from the prey, necessitating it to return to finish its job.

Capturing Prey

O. Bauri makes use of its appendages in particular for capturing its prey. And also for getting its body propelled in the air, resulting in entirely a pair of dissimilar jumps.

A "bouncer-defense leap" is when O.bauri flings itself in the reverse order, away from a prospective prey on account of its mandibles hitting an erect object.

An "escape- leap" involves the O. Bauri keeping its jaws in position facing the ground prior to launching in the air vertically.

In order to differentiate a bouncer-defense leap from an escape-leap, O. Bauri positions its head in a special manner.

Defense, Offense and Recognition

The O. Bauri species of ants are a very aggressive lot. The moment as intruder invades their habitat, several workers execute the act of jumping to escape and in case one of them happens to fall on the intruder, then the workers start to sting the intruder. However, unlike the variety of ants that belong to the Solenopsis where all the worker ants sting the intruder, here only some of the worker ants join the biting extravaganza. Their sting creates an allergy, but it is not very harmful to the human being.

O. Bauri uses antennation to identify the other worker ants from various habitats. This takes place when a pair of ants face each other by the touch of their antennae on the other ant's head or antennae. They have four various manners in which they behave when encountered with another ant. They can resort to assaulting by stinging, fundamentally become vigilant, get alarmed or attack using their mandibles.

# data[].attributes.headline
Cardboard mimic - Trap-Jaw Ant Mouthparts

# data[].attributes.subject
Cardboard mimic - Trap-Jaw Ant Mouthparts