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about the self defense, group defense, and find-
ing a prey or a competitor. Communication is an
important factor in the defense systems for all
populations of living things. One may say living
organisms use their senses to become aware of
the danger, defend their integrity to survive harsh
environmental conditions, or attack other creatures
in attempt to forage on them. Computing based
approaches and technologies allow learning more
about varied mechanisms of defense and com-
munication between living organisms.
When we mention defense mechanisms in
plants, spines may come to mind first. Most cacti
are spiny plants. Spines are modified leaves, while
thorn present in another kinds of plants are modi-
fied branches. Most of the species of a stinging
nettle have stinging hairs on the stems and leaves.
Venus flytrap catches (by a complex interaction
between elasticity, turgor - pressure in a cell
plasma, and growth and then digests (with the
use of catalyzing enzymes) animal prey, mostly
insects and spiders (arachnids).
Animals use many of their senses at the same
time to develop their defense systems that fit
their living conditions and their needs. The sense
of smell is often more acute in animals than in
humans, so most of animals manifest greater sen-
sitivity to smells than people. A skunk secretes a
foul-smelling liquid as a defense against predators.
However, many keep a skunk as a pet and playful
companion because skunks are intelligent, curi-
ous, and friendly.
The sense of touch allows the animals to feel the
harmful things but also to develop the mechanical
ways of defense and aggression. Porcupines (and
also other rodents such as capybaras and agoutis
belong here) use their sharp spines or quills when
necessary; they defend and camouflage them from
predators. The same can be told about hedgehogs
(which are also often kept as pets). Swordfish,
which usually reach ten feet in length, use their
long, flat bill to slash (but not to spear) its prey
and then catch it; they are among the fastest fish.
Moreover, they efficiently use their sense of vision
because they have excellent sight. Sea urchins,
small globular animals with radial symmetry, have
long protective spines. Starfish also have spines
covering their upper surface and a soft bottom side.
A beak, bill, or rostrum helps a bird to eat,
groom, feed young, courtship, or manipulate
objects but also fight. A shape of a beak depends
mostly on a bird's feeding method. Mammals
use teeth and claws both for defense and aggres-
sion. Many mammals, for example cattle, goats,
antelopes, use horns to defend and attack. A
horn is a projection of the skin with a bone in-
side. However, there are many kinds of hornlike
growths. Giraffes have bony bumps, deer have
antlers, and rhinoceros have keratin horns. Also
chameleons, horned lizards, some insects, and
even some jackals display horny growth on their
heads. Many mammals, such as musk deer, wild
boars, elephants, narwhals, and walruses have
tusks that are oversized teeth but serve the same
function as horns.
Chemical defense and attack include the ability
of sensing smells but also secreting, excreting, and
in some cases injecting harmful substances. Jel-
lyfish can sting their prey and inject venom; some
of them may even kill a grown man. Puffer fish
not only uses its external, spiky fins combining it
with sudden speed burst, but it also puffs up, and
many of them contain neurotoxins (tetrodotoxin)
in their stomachs, ovaries, and livers that have
lethal effect.
Spiders use chemical sensors providing infor-
mation about taste and smell and touch sensors
called setae located on their bristles. They also
use their four pairs of eyes, some of them very
acute, to detect direction of their prey movement.
Spiders defense themselves against birds and
parasitic wasps by their camouflage (a method of
concealment) coloration. Venomous spiders have
the warning coloration. Frogs defense themselves
in many ways, by camouflage, making long leaps,
or secreting mucus with diverse toxic substances
(bufotoxins) from their parotoid glands behind
the eyes. Poison dart frogs use their toxins for
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