Predation, Crypsis and Mimicry

10/12/08

   Predation:

Predation can be viewed broadly as to include all situations where one animal eats another organism (parasites do not consume the entire organism).  We usually use the terms predator and carnivore interchangeably, but in a real sense herbivores are predators as well; the difference being their prey are plants.  Let's look at some of the terms associated with predation:

There is a whole series of such terms for organisms with diets specialized in one way or another.

One generalization we can make about predators is that they help to control the size of their prey populations - and vice-versa.  The classic example is provided by the lynx and the hare.  The lynx is larger version of the bobcat, the hare in question is the snowshoe hare:

Bobcat Felis rufus

Bobcat

Snowshoe Hare (Lepus americanus)

Snowshoe Hare

Lynx and snoeshow hare population Model

The neat thing about this system is that there is a lot of data.  For over 200 years the Hudson's Bay Company has been buying pelts of these two animals and keeping detailed records of their numbers.  These data have been used to reconstruct the populations over time.  The graph above is from a model, not from the actual data, but it will serve to illustrate the presumed relationship.  First note that the population os hares regularly goes up and down.  The classic interpretation was that as the hare populations went up, it was easier for lynx to catch hares, and therefore easier for lynx to have and rear larger families, causing their populations to go up.  After a while, the increased lynx population begins to have an effect on the hares, first slowing then reversing their population growth.  With the hares in decline, the lynx find it more difficult to find food, and their populations drop due to smaller birthrates and increased death due to starvation.  Finally, with lynx populations depressed, the hares rebound, setting the cycle into motion once again.  

The problem with the classic interpretation is that it is wrong - in places where the lynx has been eliminated the hares still cycle, probably due to plants in areas of high hare populations producing chemicals that make themselves unpalatable to the hares.  This causes the hare population to decline, and eventually the plants stop producing the chemicals and allow the hares to recover.  There is no doubt that the lynx populations cycle in relation to the hare populations, but it seems apparent now that the hare populations are not responding just to the abundance of lynx.

The remainder of this web page will look at the adaptations that predators have to help them capture and consume their prey, as well as the adaptations that prey have to avoid being captured.  In terms of the latter, we will pay particular attention to crypsis (the ability to blend into the background) and mimicry (where one organism looks like another, particularly like another organism that is harmful or distasteful to the predator, even if it itself is not.

Juvenile Angelfish Christmas Tree Worms

Above - one crucial adaptation many organisms have is to disrupt the lines of the body.  In this way predators don't regognize the prey, and secondly, if they do see the organism as prey, they may not be able to figure out where the head is.  This juvenile Angelfish has stripes which break up the outline of its body.

Above right:  These Christmas Tree Worms have most of their foot-long bodies protected by the hard rock of the brain coral they are living in.  The tentacles, which resemble  trees, also have eyes and can withdraw into the rock at the slightest movement.

Right:  This Sea Egg sea urchin relies on spines and a hard shell for protection.  This one is taking the added precaution of wrapping itself int he turtle grass it is feeding on as camouflage.  Below right:  this polychaete worm, a close relative of the Christmas Tree worm, lives in the open where it is protected by sharp, poison-tipped spines which can easily break off in the attacker.  

Below:  The Lionfish, a native of the Pacific, has long, poison-tipped spines to protect itself.  Apparently, Lionfish have also been introduced to the Caribbean.

Sea Egg Sea Urchin
Lionfish Polychaete Worm
Flounder Aplaysia - Sea Hare
Peacock Flounder

Above left:  Can you spot the flounder?  Look for the eyes protruding from the sand.  Buried in this way, the flounder escapes notice by many predators.  Flounders lay on their sides; they are born like normal fish with eyes on both sides of the head, but after they decide which side will be "down", the eye with a permanent view of the mud migrates around the face so it also faces up.  The Peacock Flounder (left) is able to change the color of its skin to blend into the surroundings.

The Sea Hare (Aplaysia sp., above)) also feeds on turtle grass in tropical lagoons.  It defends itself with purple "ink" that it squirts out at predators; a moment after this picture was taken the white glove was purple (and the camera was out of film!).  Sea Cucumbers like the one at lower left can eviscerate themselves - dumping the respiratory tentacles and some of their internal organs in the face of a predator.  While the predator is busy with those, the rest of the Sea Cucumber retreats (and eventually regenerates the lost parts).  Other Sea Cucimbers have various chemical defense in the form of poisons contained in their bodies which render them unpalatable.

Below:  Spines of a sea urchin up close.

Sea Cucumber Sea Urchin
Yellowtail Snapper Baracuda

The Yellowtail Snapper (above) has a dark stripe through its eyes.  This hides the location of the eyes from predators - and breaks up the outline of the body.  Denying the predator knowledge of where the eyes are at helps to prevent the predator from knowing which way the fish will move; without that knowledge the predator is less likely to make a successful strike.  The yellow on the fins may also help direct attacks away from the vital organs, although it should be remembered that in the water yellow light is absorbed quickly and in fact the yellow coloration may be hard to see at all.  

The Baracuda at upper right is a formidable predator with sharp teeth and the ability to move quickly.  This is the type of fish the snapper is trying to avoid.  Coincidentally, this barracuda is in a heads-up position as a signal to cleaning fish that it is at this cleaning station near a coral head to have parasites removed, not to eat the cleaner fish. See the Symbiosis page for more info.

Sharks (right) of course are well-know as predators.  Specific adaptations include rows of sharp, renewable teeth, the ability to swim fast, and multiple sensory inputs ranging from the ability to sense prey moving in the water to a good sense of smell to an electrical sense that can detect the prey by the movement of its muscles, at least at close range.  

 

Shark
Sea Comb The Moray Eel (below) is a predator, but it avoids becoming prey by hiding during the day in cracks and crevices of the coral reef.  They come out at night to feed.  The Sea Combs, left, are jellyfish relatives which feed by means of tentacles which ensnare their prey.

Spotted Moray Eel

Roseate Spoonbill Yellow-crowned Night Heron

Reddish Egret

Birds face an interesting problem as predators.  Their front limbs are always busy being wings, and they have to stand on their hind limbs.  This means that they must catch and consume their food using only their beaks.  The Roseate Spoonbill (above left) uses a broad, flat bill to strain small organisms from the mud.  The Yellow-Crowned Night Heron (above) uses good night vision to locate crabs, which it then spears and cracks with a formidable beak.  The Reddish Egret (left) uses its wings to shade the water where it spears fish with its sharp beak.

The starfish (below left) crawls over its prey, a bed of oysters.  The starfish will use its strong arms to try to pry the oyster open enough so that the starfish can evert its stomach into a small opening of the oyster shell.  The stomach then secretes chemicals that kill the oyster and begin its digestion.  Interestingly, if you handle a starfish, then allow water from your hand to drip over the oyster bed, the oysters will all "clam up" - a sign they can recognize the starfish by chemical cues.

The roots of Red Mangroves (below) provide shelter from predators for many creatures, including oysters and even fish which will later swim, as adults on nearby coral reefs.

Sea Star and Oysters

Red Mangrove Roots
Right:  This damselfly larva has a unique prey-capturing device.  It's labium ("lower lip") can be shot out very quickly; in some species it may be about 1/2 as long as the body itself.  Sharp hooks on the end of the labium grab the prey, which is then drawn back to the other mouthparts which dismember it.  Al;l dragonfly and damselfly larvae have this interesting labium. Archilestes headArchilestes - Extended Labium

red-spotted newt (Notophthalmus viridescens)

Eastern Newt, Notophthalmus viridescens, Red Eft Stage - Marietta, OH
The Red Eft (above and right) is a juvenile stage of the Red-Spotted Newt, a type of salamander.  It starts life as an egg in a pond, then hatches into a gilled larva which lives in the water.  After it loses its external gills the eft strikes out to spend a year or so living on land, usually on a moist temperate forest floor where it feeds on a variety of insects.  It has potent defensive chemicals in its skin, and it advertises the fact with its bright red colors (which aren't as conspicuous on the forest floor as they are when set off against green moss, as many photographers insist on posing them.   The newt is itself a predator, feeding mostly on small invertebrates.  Eventually it will return to the water to live (unusual for an amphibian) and mate.  It loses its red color at that stage and reverts to drab green (but with bright red spots - below).

Eastern Newt, Notophthalmus viridescens, Adult - Washington County, OH

Below:  This mink (left) is a fierce predator, although here that is not prey in its mouth; this is just a mother mink carrying one of her kits to a new nest.  The mink's prey is the muskrat (below right), which it usually attacks in the muskrat's den.

Eastern Newt, Notophthalmus viridescens, Red Eft Stage - Marietta, OH

Mink with kit - North Ridgeville, Ohio

Muskrat

Porcupine (Erethizon dorsatum) Baxter State Park, Maine

Northern Saw-whet Owl - Aegolius acadicus - Maine

Alligator Snapping Turtle - Florida

Above left:  The porcupine is protected by long, sharp quills which will dislodge and attach to the predator.  The Saw-whet Owl is a nightime predator.  Its eyes are directed forward, giving it excellent binocular vision (needed to accurately judge the distance to the prey), and the ears are located such that the shape of the skull and the feathers around the face direct the softest sounds to the ears.  The large pupils admit a lot of light for nightime hunting.  In general, bird eyes are much sharper than human eyes.

The Alligator Snapping Turtle (left) has a small, wormlike protuberance on its tongue.  Fish are attracted to this lure, and the turtle snaps its jaws closed on the fish.  The shell protects the turtle; it is heavy and thick on top and much reduced on the bottom since the turtle is unlikely to be attacked from the mud.

This  Snowshoe Hare (below left) is changing from its brown summer coat to its white winter coat, the better to blend in with the snow.  Bullfrogs (below) sit quietly but can jump very quickly thanks to their long hind legs.

Snowshoe Hare - Cleveland Museum Natural History

Bullfrog (Rana catesbeiana)

Canada Geese (Branta canadensis)

Whirlygig Beetles (Gyrinidae)

Whirlygig Beetles (Gyrinidae)

Note that an adult Canada Goose's eyes are hidden in the black markings of its head.  The young, which are much more vulnerable to predators, are accompanied everywhere by the adults who will defend them.  Adult geese molt their flight feathers at the same time the young are in this helpless state.

The Whirligig Beetle (above right) lives at the surface of the water and has two pairs of compound eyes - one set above and one set below the water, to keep watch for predators such as this pike (right) approaching from either direction.

The Burrowing Mayfly (below) avoids predation from fish in its larval stage by digging into the bottom.  When it is time to become an adult, these larvae ascend to the surface en mass to emerge in large swarms, hopefully overwhelming both fish predators (in the water) and bird predators (once emerged).

Pike

Burrowing Mayfly adults

Ephemeridae - Burrowing Mayfly Larva

Daphnia sp

A real Hydra.

Fishhook Cactus Mammillaria microcarpa

The Freshwater Hydra (above right) uses stinging cells called cnidocytes which in turn have structures called nematocysts which fire small barbs into animals which touch the hydra's tentacles.  Daphnia (above left) often fall prey to hydras.

The endangered Fishhook Cactus (left) uses spines to protect itself, as does the Prickly Pear (below left).  Cacti have thick stems packed with nutrients and water - an attractive potential food source in the desert.  Further, since the stems must photosynthesize, they can't be covered with protective bark.  Thus the spines, which are actually modified leaves.

Prickly Pear (Opuntia sp.)

Barnacle

These barnacles (above) enclose themselves in hard, moveable plates into which they retreat when threatened or when they are out of the water at low tides.  The animal within is a relative of the shrimp, and feeds by waving its legs in the water; the legs are equipped with fine hairs that strain food particles from the water.  In this picture the shell of one large barnacle (with its legs partly extended) is also home to a number of smaller barnacles.

Murres

Atlantic Puffin

Many seabirds such as the Murres (above left) and Puffins (above) will nest on small rocky islands or steep rock cliffs to keep predators from their eggs.

This Ghost Crab (right) lives up to its name.  Much of its body blends into the sand, and it quickly retreats to its burrow when approached.  The Hermit Crab (below) finds an abandoned snail shell to use as a portable home; it can withdraw into the shell for protection, closing the opening with its touch claws.  Since the snail shell is no longer growing, as the Hermit Crab grows it must periodically find a new home.

Below right:  Purple Sea Stars (yes, even the orange one) approach their prey, a group of mussels on the Washington coast.  They can sense the mussels by chemical cues.

Ghost Crab

Hermit Crab

Purple Sea Star - Washington State

Brown Pelican

Great Egret

Brown Pelican

Feeding in birds:  Birds prey on a number of different animals, in fact many birds are predators, in part because it is hard to digest plant material and it would be hard to fly with a large stomach filled with fermenting leaves.  Birds that do feed on plants tend to concentrate on easier to digest seeds and fruits.  

The egret (above) is a sit-and-wait predator; it remains motionless and waits for fish, frogs, or even insects and other invertebrates to come in range.  The Brown Pelican (left, above left) flies over the water and dives into a school of fish, which it captures in its throat pouch.

The American Oystercatcher (below, left)  uses its long bill to probe the sands for bivalves, its prey.  The Black Skimmer (below, right) is unusual in that its lower bill is longer than the upper one.  It drags the tip of the lower bill in the water to catch fish on the fly.

American Oystercatcher

Black Skimmer

Sea Lamprey (Pacific, not Atlantic)

Corydalus sp. - Hellgrammite
The Lamprey (above) does not have jaws but instead has a round, sucker-like mouth with teeth.  It attaches to the side of a fish and rasps through the skin to feed on softer tissue and blood.  Some adult lampreys do not feed at all, however.  

The Hellgrammite (upper right) is an insect larva that preys on other insects that it finds hiding under rocks in streams.  Its flat shape helps it get into the crevices where its prey hides.  In such a world, the stony armor carried by the 3 caddisfly larvae pictured here (right and below) makes a lot of sense.  These larvae, kin to caterpillars, also spin silk; they use the silk to bind together small stones, twigs and leaf particles to form a traveling case.  The case provides both ballast and some protection, if for no other reason than it tends to blend in with the other debris on the bottom of a stream, and if a predator would come in contact, all of their senses - touch, chemical, sight - would tell them that they were just encountering some nits of rock.

Caddsfly larva with case

Caddsfly larva with case

Helicopsyche sp. - Snail Case Making Cadissfly

American Bison Calf

American Bison - Theodore Roosevelt National Park

Cheetah

The American Bison, above, finds protection in large herds.  While an individual, particularly a calf like the one to the left, might be in danger from predators such as a pack of wolves, a large herd is much more formidable.

Left:  A Cheetah relies on speed and stealth to approach its prey and overcome it before it can run too far.  This one was actively stalking a replacement zoo worker at a zoo during a strike - who knew cheetah were unionized?

Rhinos (below left) are too big to be threatened much by cheetahs, which feed on smaller, lighter prey such as gazelles and antelope.  It would be interesting if the cheetah and the pronghorn (below) lived in the same habitat;  the cheetah is the fastest land animal with top speed of about 70 mph and the pronghorn second fastest at 61 mph.  The pronghorn, however, can run for considerable distances at speed.   I take all these speed records with a grain of salt.

Rhino

Pronghorn

Mule and Mountain Lion

White Rhino
Above - two unusual defensive strategies.  The mule is swinging the body of a mountain lion.  Horses in general are very capable of biting, and, as the picture shows, can lift a pretty good weight.  This picture has been all over the web and I forget where I stole it from, but it is not mine.  It is usually accompanied by a story of how the mule killed the mountain lion, which apparently isn't true.  Above right:  approach a rhino from either end and you are screwed.  Right and below right:  The juvenile Red-tail hawk to the right spent a winter on our campus and pretty much decimated the squirrel population.  The adult red-tail below right is shown soaring; the sharp eyes of hawks have almost 8x the visual acuity of the human eye and this allows them to spot their prey from the air or a high perch.

Many spiders are among the classic sit-and-wait predators; they use strands of silk to capture their prey, which they then finish off with a venomous bite.

juvenile Redtail Hawk

Spider

Redtail Hawk

Milkweed Bugs

Milkweed

Milkweed Beetles

Animals are not the only ones with defenses against predators, remember that an herbivore is a predator - if you are a plant!  The milkweed (above) has a potent mix of chemicals including glycosides to deter feeding by insects and other herbivores, and it also has latex in its stems and leaves.  The latex gums up the mouthparts of insects.  Still, a number of insects have found a way around the chemical defenses of the milkweed.  Many of them incorporate the milkweed's defensive chemicals into their own bodies, and they warm potential predators of their chemical defense through the use of bright colors and bold patterns.  The Milkweed Bug (above left) and the Milkweed Beetle (left) are examples of insects which can feed on milkweed and which have warning, or aposematic, coloration. 

The Dogbane Leaf Beetle (dogbane being a type of milkweed) is very attractive if not aposematic (below left).  Ladybird beetles (below) also are often brightly colored and many have chemical defenses.  If you rub one (gently)  between your fingers you will notice a distinct odor left behind on your fingertips.

Dogbane Leaf Beetle

Ladybird Beetle

Monarch Caterpillar

Monarch Chrysalis
The Monarch Butterfly in 3 of its incarnations:  Above left, a Monarch Caterpillar feeding on a milkweed leaf.  Above right, the Monarch Chrysalis in which the Monarch Pupa completes the transformation to the adult Monarch Butterfly (right).  All three of the life stages are protected by the chemicals the larva acquires from the milkweed.  

Below, two photos of the Viceroy Butterfly.  Long thought to be a harmless mimic of the unpalatable Monarch, it turns out that a number of Viceroy Caterpillars - but not all - do in fact feed on plants with chemical defenses and incorporate them into their own bodies, making them unpalatable as well.  The original scientific studies that found the Viceroy to be palatable were flawed in that the caterpillars were fed an artificial diet that lacked the chemicals the caterpillars would normally ingest.  In any event, what was thought to be an example of Batesian mimicry (where a palatable species mimics an unpalatable one) has been show to actually be MŁellerian mimicry, where two equally unpalatable species converge on a common color pattern to make it easier for predators to learn which organisms to avoid.

Monarch Butterfly Adult

Viceroy Butterfly Adult

Viceroy Butterfly Adult

Mountain Goat

Grouse Chick

Toad - American? Fowler's? Hybrid? Baxter State Park, Maine

The mountain goat (above left) avoids predation by living in remote areas and by blending in with the rock and snow of that habitat.  The horns aren't a handicap when it comes to defense, either.  The grouse chick, above, blends into leaves on the forest floor, as does the American Toad (left) and Fowler's Toad (below left).  The toads have a backup defense in the form of a number of poisonous chemicals stored in glands in their skin.  In particular, the large parotid glands behind the eyes are major sources of the protective poisons.  In some species of toads (not these) the poisons are psychedelic in humans, but before you lick a toad remember that another defense used by toads (and many small animals) when being handled is to urinate on their captors.

Below right:  What is the LAST thing a bird would eat?  Bird poop.  The bird dropping caterpillar takes advantage of this.  It sits coiled on the leaf it is nibbling on while birds look right past it.

Fowler's Toad (Bufo woodhousii fowleri)

Bird-dropping Caterpillar

Copperhead Snake - Agkistrodon contortrix - Lowry Park Zoo, Tampa

Gray (or Cope's) Treefrog - Hyla versicolor,  Carroll County Ohio
The Copperhead (above) uses poison to overcome its small mammal prey.  Even more interesting is how it finds the mammals, particularly at night.  If you look carefully between the eye and the nose (and just a little down), you will see a small pit.  This pit is lined with cells sensitive to heat, and this heat sense allows the snake to "see" and strike at warm-blooded prey.  Apparently some squirrels can increase blood flow to their tails, amkeing them hotter and confusing the snake, making the squirrel look bigger and causing the snake to back off. 

The Gray Tree Frog is well camouflaged on a lichen-covered tree trunk, but it has a backup, poison in the skin.  If a predator does find it, the frog will flash the undersides of its thighs, which are bright yellow, to warn the predator off.  You can see just a touch of this yellow on the hind legs. 

The tent caterpillars at right huddle in a communal nest spun from their own silk by day, and venture out at night to feed.  This reduces risk of attack by birds.

Millipedes often have defensive chemicals, even cyanide, and this one is aposematically colored.

The Luna Moth, below is a fascinating case.  Moths usually fly at night, so they don't have to worry about birds.  But bats fly at night, and they find their prey by sonar, not sight.  What's a moth to do?  Evolve ears.  Many moths can hear the bats' ultrasonic sonar and, depending on the moth and the conditions either move away, drop rapidly to the ground, or in some cases produce ultrasonic noises of their own to "jam" the bats' sonar.

Eastern Tent Caterpillar, Malacosoma americanum

Luna Moth Adult

Millipede

Pinching Bug (Pseudolucanus capreolus) - Avon, Ohio

Hickory Horned Devil Caterpillar

12-spotted Tiger Beetle, Cicindela duodecimguttata, Washington County, Ohio

The large jaws (mandibles) of the stag beetle (above left) are not used for catching prey, or even for defense - they are used by the males to wrestle for females.  You have to be careful sometimes in how you interpret features.  On the other hand, the spines on the Hickory Horned Devil (above) are used for defense.

The Tiger Beetles (left) are predators which grab smaller invertebrates with their large jaws.  The upper one blends in well with sands and bits of coal on a stream bank; the lower one is conspicuous when it hunts on a woodland trail but quickly disappears into trailside vegetation.

The Paper Wasps (below) are helpless as larvae (bottom) and pupae (middle); these stages live in the hive and are guarded by the adults (top) which, of course, can sting.

6-spotted Tiger Beetle (Cicindela sexguttata) - Indigo Hill, Washington County, Ohio

Paper Wasp - Polistes sp. - Avon, Ohio  Adult, Pupa, Larva

Periodical Cicada - Magicicada sp.; Washington Co. OH - Brood V, 1999

Periodical Cicada - Magicicada sp.; Caught by female Cardinal, Washington Co. OH - Brood V, 1999
The 17 year or Periodical Cicada (above) has an interesting antipredator defense.  At any one time, in any one place, all of the cicadas are the same age.  They spend 17 years underground and emerge in huge numbers - I collected the 5-gallon bucket seen at right in a few hours.  During the emergence, birds and other predators eat their fill (above right), and they end up raising a lot of babies.  The next year, however, when all those baby birds are out to feed their own babies, the cicadas are all safely underground feeding on plant roots - they won't be where the birds can get them for another 16 years, by that time the bird baby boomlet will be long gone.

The Dog-Day Cicada (below right) is similar in many ways.  It lives underground for 13 years, but a bigger difference is that its cohorts overlap.  At any time, there are cicadas which have been underground 13, 12, 11, 10... years, thus a few are available to emerge every year.  They have to avoid the birds and their green color may help with this.

The Oak Treehopper (below) feeds on plant juices above ground.  It blends into the tree, looking like a thorn.  Question - if this herbivore, by looking like a thorn, causes other herbivores to avoid the tree, might this be a mutualistic relationship?  Think about it!

Periodical Cicada - Magicicada sp.; Tippecanoe County, IN

Oak Treehopper - Platycotis vittata - Marietta, Ohio

Dog-Day Cicada - Tibicen sp.

Gaudy Leaf Frog - Agalomis callidryas - asleep

Ameiva festiva - Whiptail Lizard

Gaudy Leaf Frog - Agalomis callidryas - Female with male

Many small lizards have a bright blue tail.  This paradoxically attracts the attention of predators, but at least the predators are attacking the wrong end of the animal.  Further, in many lizards, the tail can be dropped from the body when the lizard is under attack.  The predator ends up confronting (and probably eating) the still-wriggling tail, while the lizard escapes to regrow its tail.

The Gaudy Leaf Frog (left) does not live up to its name during the daytime.  It lies flat, exposed on the surface of leaves in the rainforest.  This position hides all the bright-colored body parts, and also reduces evaporation (admittedly not as much of a problem in the rainforest as it would be in a desert).  The animals come to life at night (left) and the transformation is amazing as the red toes and eyes and blue sides come into view.  Of course, what is the use of all that color if you only show it off at night?

Dendrobates pumilio - Blue Jeans Dart Frog

Leptoplius ahaetulla - Central American Parrot Snake

Dead Leaf Mimic Katydid

Another strategy used by many rainforest frogs is demonstrated by the Blue Jeans Dart Frog (above left).  These frogs pick up poisons from their invertebrate prey and store them in their skin.  They advertise this defense with bright, aposematic colors, and they forage during the day under this protection.

Defenses don't always work, however.  This frog (above) has fallen prey to a Central American Parrot Snake.  Imagine the difficulties for the snake - capturing a slippery, fast jumping prey from a perch high in the rainforest - and then swallowing it - all without falling to the ground - and without legs!  Many small, sharp, inward pointing teeth, combined with jaws that can unhinge to allow large items to be swallowed, help the snake pull off this feat.

Despite chemical defenses, many plants become targets for herbivores (below).  Many of these herbivores are Orthoptera, a group which includes grasshoppers, locusts, crickets and katydids.  The katydids are very interesting; they often mimic leaves and remain motionless during the day, just blending in.  They move about and feed mostly at night, when most of the birds are roosting.  The katydid above resembles dead leaves found on the forest floor.  Even more amazing is the katydid to the right - it looks like a living, green leaf, but one that has been damaged (by katydid feeding?)!  Even the veins of the wing have been rearranged to resemble the vein patterns normally seen in plant leaves. Damaged Leaf Mimic Katydid

Cecropia leaves with insect damage

Damaged Leaf Mimic Katydid

Ctenosaur

Roadside Hawk - Buteo magnirostris

Green Iguana

The Ctenosaur (above left) is large enough that it has relatively few predators; still, it blends in with the trees and leaf litter of its tropical dry forest home.  Green Iguanas (left), particularly when they are young, are bright green to blend in with the leaves of the trees they live in.  They also tend to bask on branches over water, and will not hesitate to drop tens of meters into water below if approached by a predator.  The Roadside Hawk (above) has caught a small anole that didn't blend in with its background quite enough to overcome the bird's excellent vision.

Giraffes, below, live on the Savanna, where grasslands intersperse with patches of trees (where the giraffes feed; they didn't develop those long necks to feed on grass!).    To our eyes, the giraffe (below left) are fairly brightly colored and stand out, but remember that the the predator the Giraffe is more worried about is the lion, and like most mammals, the lion's eyes are adapted to see at night.  This means they have more rods than cones, and it is the cones that give us color vision.  Thus, to the lion, the giraffe probably looks more like the image below right.  In this case, the giraffe blends in amazing well with the background.

Giraffe

Giraffe

Scorpion

Scorpion
Scorpions are nocturnal predators that overcome their mostly invertebrate prey with the help of a poisonous stinger located on the tip of the tail.  The scorpion holds its prey with its front claws, then brings the tail forward to sting the prey; the prey is then dismembered by the other mouthparts in a very messy process.   The sting, of course, is also a potent defensive weapon; people have died from scorpion stings.  On the other hand, a number of organisms feed on scorpions, note the army ants carrying off a scorpion to the right.

For more on scorpions, click here.

Below:  Can you spot the camouflaged moth on the tree trunk?  Moths are usually inactive during the day and need to be difficult to spot during the day.

Army Ants with Scorpion

Moth

Moth

Inca Dove - Columbina inca

Bufo marinus - Giant Toad

Army Ant Soldier

The Inca Doves (pictured above left) have feathers which create an amazing, three-dimensional camouflage patterns.  The Giant Toad (above) has enormous parotid glands behind the head.  This, combined with their large size, enables them to deliver a large load of poison.  Since they have a habit of taking pet food from pet dishes left outside at night they are drawn into conflict with those pets.  Some dogs have died due to toad poisoning. 

Army ants (left) are formidable predators (mostly on invertebrates).  What they lack in individual size they make up in huge numbers.  To gain some appreciation for these predators, take a look at the Army Ant Page.

Below left:  A Gopher Tortoise in Florida is doubly protected - first by its large size and tough shell, secondly by the 10 meter long burrow it constructs underground.  The burrow helps it maintain a constant temperature, and in addition to protecting the turtle from predators it keeps it safe from the fires that normally occur in the Florida Scrub habitat.

Gopher Tortoise

Green Anole - Anolis carolineaus Brown Anole - Aolis sagrei

Pufferfish

Above:  two related lizards, two camouflage schemes.  The Green Anole (left) maintains a bright green color when the lizard is warm and actively darting around on plant leaves.  This ensures it will blend in with the green of the vegetation.  The anole on the right - the Brown Anole - spends more time on the ground and on tree trunks, so it maintains a brownish, patterned color that also breaks up its outline.  At night, when things cool off, the Green anoles retreat to hiding places on tree trunks and on the ground, and at this time their skin color also changes to brown.

The Pufferfish (left) has sharp spines which are made even more effective when the body is full of water or air.  With the body swelled, the spines stick straight out, and the increased size makes the  Pufferfish hard to swallow, even if the predator can stomach the spines.

We've already mentioned venom in conjunction with the copperhead; both of these snakes are also venomous (and both are also pit vipers - can you spot the infrared-sensitive pits?).   Both of these snakes were along trails - a common strategy of sit-and-wait predators is to stake out an area that the prey is liable to come to and wait.  In this way, energy is not expended looking for prey.  Note also the vertical pupil; characteristic of animals that hunt by night. Bothrops asper - Fer-de-lance

Porthidium nasutum - Hog-nosed Pit Viper

Right:  To pictures of the same toad, taken a few hours apart.  This Oak Toad has the ability to greatly darken or lighten its color; Marietta College student Andrew Rosendale determined in 2007 that Oak Toads and American Toads lighten or darken in response to the color of their surroundings.  This helps increase their camouflage and is particularly crucial for hatchling toads which are preyed upon by a wider range of predators than the adults.  One last toad trick - most toads can swallow air and puff their bodies up, wedging themselves into cracks or, like the pufferfish, making themselves too big to swallow.

Bufo quercicus - Oak Toad

Hyla versicolor - Gray Treefrog Tadpole

The Gray Treefrog tadpole at left has a bright red tail.  Studies suggest that the red tail only develops in individuals in ponds with predators; other studies show that the tail is effective in directing the predators' attacks towards the tail and away from the more critical head.
The Spicebush Swallowtail caterpillar (right) is capable of mimicking a much larger animal - a snake.  Read more about this mimic here.

Summary: Interactions between organisms:

 

 

Effect of Interaction On:

Type of Interaction

Species 1

Species 2

Competition

(-)

(-)

Predation

Predator (+)

Prey (-)

Parasitism

Parasite (+)

Host (-)

Herbivory

Herbivore (+)

Plant (-)

Detritivory

Detritivore (+)

Detritus (0)

Commensalism

(+)

(0)

Mutualism

(+)

(+)