Download A tick is a small, blood-sucking mite. Normally it lives on blood from

A tick is a small, blood-sucking mite. Normally it
lives on blood from dogs, sheep, birds or other
larger animals, like deer and cattle. It may also
attach itself to humans. When feeding, ticks make
a small hole in the skin, attach themselves with a
modification of one of the mouthparts which has
teeth that curve backwards, and insert barbed
piercing mouthparts to remove blood. Ticks also
serve as vectors for many diseases. For example,
the American dog tick may carry Rocky Mountain
spotted fever, tularemia, and other diseases that
can also be harmful to humans.
Many kinds of aphids secrete a sweet substance
called honeydew, prized as food by ants. This substance
consists of partially digested, highly concentrated plant
sap and other wastes and is excreted from their anus,
often in copious amounts. In this relationship, the ants
herd the aphids to the plants that the aphids use as a
food source at the appropriate stages of the aphids' life
cycle. They move aphids around to the most succulent
branches, while keeping the aphid's natural predators at
bay. The ants also
shelter the aphid eggs in
their nests during the
winter. The aphids, in
turn, provide honeydew
for the ants. The ants
collect the sweet liquid
and bring it home to
feed the colony.
Clown fish are bold, because they dare to live in
places where most marine animals dread to go near.
Indeed, their choice of residence, a sea anemone, is an
immobile, underwater creature that snatches a passerby
with its waving, poisonous tentacles! The clown fish
capitalize on being an anemones' roommate because if a
predator continues their pursuit, it will quickly regret its
decision -- instead of being a hunter, the predator
becomes a fallen prey to the clown fish's protector. So,
how can the clown fish avoid getting stung by the sea
anemone? Well, it turns out that the clown fish has a
special layer of mucus on its skin. Miraculously, this layer
of mucus gives it immunity. There are also other factors
that bring the clown fish and the anemone together. For
example, the clown fish eats leftover bits that the
anemone discards. In return, the anemone receives a free
cleaning service.
A gall is a plant structure formed by
abnormal growth within plant tissues in
reaction to being infected by certain organisms
such as bacteria, fungi, nematodes, mites, or
insects. These gall-makers usually secrete
enzymes or plant hormones that stimulate
hypertrophy (over-growth) and/or hyperplasy
(cell proliferation) in their host plant. The
resulting structures are quite distinctive and
highly species-specific, ranging
in size, color, and location on
the plant. The gall-causers do
not destroy the plant, but
slowly utilize its nutrients.
Lions are extremely powerful: by using
only a grip on its rump, they can grab and
throw a fully grown zebra. A heavy blow to
the head of a zebra using a forepaw is
sufficient to stun the animal. The lions most
frequently used killing technique is a
suffocating hold on the muzzle. Usually the
kill is clean and quick, with little tearing or
biting. Team co-ordination is important,
particularly with larger prey: some lionesses
may distract the prey while others bring it
down.
Lichens are symbiotic associations of a fungus with
a photosynthetic partner called a photobiont. The
photobiont, usually green algae, produces food for the
lichen from sunlight. The symbiosis is considered
obligatory for successful growth and reproduction of
the fungus; however, the significance for the algal
photobiont is less clear. For some algae, the symbiosis
may be obligatory for survival in a particular habitat
because the fungus part of the lichen helps absorb
water and minerals from whatever the lichen is
growing on. The algae then uses these materials to
make food for itself and the fungus. However, in other
cases, there is evidence that the relationship might be
a disadvantage for the algae, since the algae may be
able to grow faster when not associated with the
fungus.
Remoras (also called suckerfish) are a group
of elongated brown fish in the family Echeneidae.
Their dorsal fin takes the form of a modified oval
sucker-like organ that can take a firm hold
against the skin of a larger marine animal. The
sucking disc begins to show when the young fish
are about 1 cm long and is fully formed when the
remora reaches about 3 cm. Remoras are
commonly found attached to sharks, manta rays,
whales, and turtles. Some small remoras travel
in the mouths or gills of large sunfish, swordfish,
and sailfish. The host they attach to for
transport gains nothing from the relationship, but
also does not lose anything. The remora’s diet is
primarily leftover fragments or sometimes the
feces of the host.
Mistletoe is the common
name for various plants
belonging to the order
Santalales. The European
Mistletoe is readily
recognized by its smoothedge oval leaves and white
berries in dense clusters.
The American Mistletoe is
similar but has shorter, broader leaves.
Mistletoe grows on a wide range of trees,
and utilizes the host mainly for mineral
nutrients from the ground. This usually
results in a reduction of growth of the host
tree. Where infestation is heavy, mistletoe
can cause the death of its host.
Escherichia coli,
usually abbreviated
E. coli, is one of the
main species of
bacteria that live in
the lower intestines
of mammals. While the host organism
provides an appropriate habitat and nutrition
source, the bacteria are necessary for the
proper digestion of food for mammals. The
presence of beneficial bacteria in the
intestines also helps synthesize vitamins and
inhibits the growth of disease-promoting
pathogenic bacteria.
The number of
individual E. coli
bacteria in the feces
that one human
passes in one day
averages between
100 billion and 10
trillion.
Heartworms are a type of roundworm that
can infect dogs, cats, wolves, coyotes, foxes, and
other animals. As adults, they are about six
inches long. The name comes from the fact that
the final reproductive stage of the worm’s life
cycle takes place in the heart of its host. Adult
male and female worms living in the heart
produce thousands of microscopic baby worms
which circulate throughout the
body. An intermediate host
(typically a mosquito) then
picks up the baby worms and
spreads the infection to more
host organisms. The
heartworms can live in the heart and large blood
vessels of the host for many years, but usually
kills its host in the end through congestive heart
failure.
Termites, also known
as white ants, feed on
cellulose, in the form of
wood and other dead
plant material. They are
economically important
pests that can cause
serious structural
damage to buildings and
crops. Termites are vital,
however, in tropical
regions where their
recycling of wood and
other plant matter is of
ecological importance.
The termites rely
primarily upon symbiotic
protozoa that reside in their guts in order to digest
the cellulose. The termites then absorb the end
products for nutrition. In addition, the protozoa rely
on bacteria embedded on their surfaces to produce
some of the necessary digestive enzymes.
microscopic
protozoa from the
hindgut of termites
The cattle egret, the
only member of the genus
Bubulcus, is a small white
heron that is found on all
continents except
Antarctica. The species on
average is 50 cm long and
weighs 200-600 grams.
These birds are often
found riding on the backs
of cattle and other large animals in dry, grassy
habitats. Cattle egrets feed on insects, especially
grasshoppers. These insects are usually
disturbed and become visible from the movement
of the cattle. The egrets
may also benefit from the
protection of a larger
animal. The cattle in this
relationship are unaffected.
Pseudoscorpions are small arthropods with a flat,
pear-shaped body, eight segmented legs, and simple
eyes. They have two very long pincers, which resemble
the scorpion’s claws, but the pseudoscorpion’s abdomen
is short and rounded at the rear, rather than extending
into a segmented tail and stinger. They range from 2 to
8 mm in length. The pincer contains venom that is used
to capture and immobilize their prey, which may consist
of mites, ants, and booklice. To digest the prey, they
pour a mildly corrosive fluid over the prey and then
ingest the liquefied remains. Pseudoscorpions also have
a relationship with larger insects by using these
organisms as temporary hosts for transportation
purposes. The larger insects are not harmed in the
process. Pseudoscorpions are often found in bathrooms,
closets, firewood, and among old books.