Download SCIENCE AND NATURE Lotsa confusium The Classification System

SCIENCE AND NATURE
SCIENCE 1. Knowledge about nature and the universe. Science
seeks explanations of how animals and things work and
live. This knowledge comes through experiments and
from careful observation of the world. 2. Any particular
branch or area of knowledge in which observation, experiments, and study are utilized.
Lotsa confusium
Question: The name of this animal is:
A. woodchuck
D. whistle pig
B. groundhog
E. all of the above
C. Marmota monax
Answer: E. all of the above !
What’s the difference between a woodchuck and a groundhog? How about a groundhog and a
whistle pig? Nothing — all three
are the same animal! Each name
is a common name for the mammal
Marmota monax. Many common
names for the same animal can be
very confusing. Add to this the
troubles that may arise if several
biologists work on the same project
and each speaks a different
language! With nearly one million
species of insects and hundreds of
thousands of other animals and
plants, one system and language
for naming organisms is a
necessity.
The Classification System
Most of the credit for introducing the system that is presently in use is given to an 18th
century Swedish biologist named Carolus Linnaeus. He instituted a "binomial" (two-name)
classification system to organize the animal and plant kingdom based on structural similarities. The present day hierarchal classification system is divided into seven major categories;
each category contains organisms that uniquely share certain features. The categories are
arranged in levels that become more specific concerning the similarity of the organisms within
them as we move from the highest level of Kingdom to the lowest level of Species.
Classification of the house fly using Linnaeus’ system:
Level
Taxa
Kingdom Animalia
Phylum Arthropoda
Class
Insecta
Order
Diptera
Family
Muscidae
Genus
Musca
Species
domestica
The words in the classification of the house fly may not look familiar to you because they
are in Latin. Linnaeus was so fascinated with the Latin language that he changed his original
name of Karl von Linne into the Latin form, Carolus Linnaeus. Linnaeus chose Latin as the
language of his binomial naming system because it was the universal language of scientific
scholars of his day. He also realized that people all over the world would need to use this system, and one universal language would allow everyone to discuss the same plant or animal
without the “whistle pig/ woodchuck” confusion.
When scientists talk about an animal, it would be a waste of time to use all seven levels
of the classification system. To remedy this problem, Linnaeus created an abbreviated version
of the system which is now called the scientific name. The scientific name of an organism
is made up of two parts; the Genus and species.
Aix sponsa
Wood Duck
Botia sidthimunki
Lohachata Loach
GROUPIES
The study of grouping and
classifying living organisms
is called taxonomy.
Salmo salar
Atlantic Salmon
Alligator mississippiensis
American Alligator
Crotalus horridus
Timber Rattlesnake
Egretta tricolor
Tricolored Heron
MONERA
single-celled primitive organisms lacking a
nuclear envelope, mitochondria, and
chloropoasts
KINGDOM
blue-green algae, bacteria
PROTISTA
single-celled or colonial organisms possessing a nuclear envelope and mitochondria; some are capable of switching from
autotrophic to heterotrophic depending on the conditions
KINGDOM
amoebas, diatoms, euglenas
FUNGI
organisms that digest their food externally
and absorb it through their body walls
KINGDOM
slime molds, mushrooms
PLANTAE
organisms that are able to make their own food using energy from
the sun, water, and carbon dioxide gas from the air in a process
called photosynthesis
KINGDOM
green algae, red algae, brown algae, mosses, horsetails, ferns, conifers, flowering
plants
ANIMALIA
organisms that can obtain their own food
KINGDOM
Phylum
Porifera
sponges
Aschelminthes
nematodes,
rotifers
Bryozoa
bryozoan
Cnidaria
jellyfish, sea
anemones, corals,
hydras
Platyhelminthes
flatworms, flukes,
tapeworms
Class
Diplopoda
millipedes
Chilopoda
centipedes
Arthropoda
Annelida
earthworms,
marine
worms,
leeches
Insecta
insects
Mollusca
snails,
clams,
octopus
Echinodermata
sea stars, sea
urchins Chordata
Arachnida
Crustacea
spiders, crabs, barnacles,
scorpions crayfish, woodlice
Class
Agnatha
lampreys,
hagfish
Chondrichthyes
sharks, skates,
rays
Osteichthyes Amphibia
frogs, toads,
bony fish
salamanders,
newts
Reptilia
turtles,
snakes,
lizards,
alligators
Aves
birds
Mammalia
primates,
bats,
dolphins,
rodents
This is a partial listing of phyla and classes. The bold groups are discussed in more detail in this chapter!
Budding Taxonomists!
The variety of species in the animal kingdom is phenomenal. From iridescent jellyfish to
diving spiders and sloths that hang upside down all day - there are animals that amaze, that
surprise, and that wait to be discovered. They are in nearly every body of water on earth, each
mountain range, and every continent. Linnaeus’ system helps us make sense of this immense
and dizzying array of animal life on earth.
The Tennessee Aquarium is home to animals from around the world, and at first it may
seem overwhelming to try to learn about each exhibit and its inhabitants! The way to get
started is to observe the animals carefully. How are they different from each other? How are
they similar? Using the chart on the preceding page and the following summaries you will
soon begin to “classify” the animals yourself, based on the characteristics you have
observed. Is it a reptile or an amphibian? A fish or a mammal?
Be curious and patient -- there are exceptions to nearly every rule in
nature, and things may not always be as they appear! But the study of the
living world around us, whether it be the spider in the cellar of your house
or an octopus in a coral reef, is bound to be the most rewarding and challenging
adventure on which you will ever embark.
ANIMALS, ANIMALS, ANIMALS!
To Have a Spine or Not...
What do bumblebees, snails, worms, and jellyfish have in common?
This diverse group of animals all lack a backbone. They belong to an enormous collection of
organisms called invertebrates. About 95% of all known species of animals on earth belong to
this group. They range in size from the microscopic amoeba to the giant squid that reaches a
length of nearly 60 feet!
The remaining 5% of earth's species are classified within the phylum chordata. These
animals possess a backbone and are called vertebrates.
ARTHROPODA
The phylum Arthropoda is the largest phylum. It
contains about 900,000 described species, which range
from microscopic insects to crabs with legs that are 3 feet
long.
WHAT'S IN A NAME?
The word arthropod is derived
from the Greek arthron podos
which means “joint-feet.”
No matter their size, arthropods characteristically
have paired jointed limbs and a hard outer covering
called an exoskeleton. The protective exoskeleton contains chitin, a strong and flexible material. In order to grow, an arthropod must periodically
shed its exoskeleton and grow a new one which will expand and harden into a larger size.
Crustaceans
The 39,000 species of the class crustacea are distributed worldwide and include the
familiar lobsters and crabs, as well barnacles, fish
lice, and other small relatives that are the major
components of plankton. Most crustaceans
are aquatic with the majority living in
marine environments. They most often
breathe through gills or through the body
surface. In many crustaceans the blood
contains hemocyanin, a copper-based pigment that carries oxygen. Hemocyanin is
somewhat like mammalian hemoglobin.
Crayfish
Crustaceans have two pairs of antennae
which are usually sensory but may also be
used for balance, mating, or locomotion.
CRUSTACEANS AND PEOPLE
Crustaceans have a two-fold economic importance to humankind. Foremost they have a strong commercial value
as food. Shrimp, lobsters, and crabs are harvested from the
sea and have also become popular aquaculture products.
Tiny krill are now being harvested and processed as food
for livestock. On the negative side, crustaceans can be
costly foulers of coastal structures and ships. Barnacles
attached to a ship’s hull can increase the possibility of
corrosion, as well as create enough drag to increase the
ship’s fuel costs by 40%. Crustaceans may clog watercooling intake pipes of coastal industries, or weaken piers
by boring into the wood.
QUESTION: How many
pounds of tasty crayfish does
it take to satisfy the appetite
of the people in Louisiana?
ANSWER: To keep up with
the demand for the craved
crustacean, nearly 2 million
pounds of crayfish are caught
in traps yearly, and an additional 2.6 million pounds
raised by aquaculture!
Insects
The class Insecta contains more species than any other class of animals - more than the
plant kingdom and the rest of the animal kingdom combined! There are approximately
800,000 known species of these small invertebrates, and many more are being cataloged and
named as they are discovered. Insects are successful in nearly every habitat, including mountain tops, in valleys, in the air, in fresh water, in the sea, and underground. They range in size
from the microscopic to the enormous noctuid moth with a wingspan of 11 inches, and come
in every color imaginable. Despite the amazing variety of the insect world, most individuals
share the following characteristics:
BODY DESIGN
The insect's body is composed of three parts: the head, the abdomen, and the thorax.
There is usually one pair of sensory antennae, 2 eyes, 6 legs, and 2 pairs of membranous wings.
CHEW, SLURP, PIERCE, BITE...
head
Insects have specialized
mouthparts depending upon
the type of food that they
antennae
eat. Butterflies feed
mainly on flower nectar,
so their mouthparts
include long coiled tubes designed for sucking. Mosquitoes
have mouthparts that are designed to
pierce animal skin and suck liquid. Termites
and grasshoppers both have biting and chewing
jaws. The possibilities are as numerous as there are
types of food to eat!
abdomen
thorax
wing
walking legs
LEGS AND MORE LEGS
Most species of insects have 6 legs, but the structure of these legs
varies greatly depending on the species. By examining an insect's
legs, it is possible to predict how the legs are used. The long, slim
legs of a cockroach are good for running, whereas powerful
enlarged back legs are indicative of jumpers such as grassCockroach
Water Beetle
Grasshopper
hoppers and crickets. Swimming insects like the diving beetles have legs that are enlarged at
the tip or covered with tiny hairs. Some beetles that burrow into soil have spines or bristles on
their legs that act as shovels or brooms.
GROWING UP
Most insects go through a series of physical changes, known as metamorphosis, as they
grow from egg to adult. In some cases the changes are subtle, and the young look similar to the
adult. Insects such as the moth and butterfly, however, undergo a complete metamorphosis
as they develop from caterpillar to the adult form. The immature stages of some species are
often found in the aquatic environment, and the emerging adults head to land for a terrestrial life.
BENEFICIAL BUGS!
Many insects are beneficial to humankind. Some directly provide
usable products such as honey, beeswax, and silk. Several thousand
plant species, including many commercially grown varieties, rely on
insects for pollination. Other insects help to replenish the richness of
the soil by burrowing or breaking down plant and animal matter.
Insects are also an important food source for animals such as birds,
bats, frogs, lizards, snakes, fishes, and even bears!
CHORDATA
Bats, sharks, eagles, frogs, and humans - at first glance these animals seem to share
very few characteristics. Linneaus grouped these seemingly dissimilar animals together,
however, because they all possess a common trait - the presence of a backbone. The phylum
chordata is highly diverse with members successfully inhabiting the air, the land, and the
water. While the invertebrate groups contain more species and exist in greater numbers, the
vertebrate species are generally larger in size and structurally more complex.
Birds
Birds range in size from the little bee hummingbird that can fit into a matchbox to the
ostrich that stands over 8 feet tall. Some can fly backwards, some can hover, while others cannot fly at all! They come in an astonishing array of shapes and colors, but the one common
characteristic that sets all birds apart from any other vertebrate is the development of feathers.
Made of a strong and flexible protein called keratin, feathers provide thermal protection as well
as assist in streamlining the bird for flight. The bright colors of some feathers are created by
actual pigment. Other feathers, such as those of the macaws and the peacock, actually bend
light to create shimmery colors.
The beak of a bird is used in nest building,
feather preening, combat, and food gathering.
Different foods require different beak designs.
Birds of prey, for example, have hooked beaks that
are used in tearing apart animals that are too large
to be swallowed whole.
.
Courting behaviors of birds are often complex and elaborate. After mating, the female lays
eggs which are usually incubated by one of the
parents until the chicks hatch. Some chicks can
fend for themselves immediately, while others are
dependent on the care of the adults.
The cardinal's strong coneshaped beak is used to
crack open the hard shells
of seeds.
The heron can spear
frogs and fish with its
sword-like bill.
The long upcurved bill
of the avocet is used to
dislodge bits of food
from river bottoms.
Amphibians
WHAT’S IN A NAME?
The word amphibian is
derived from the Greek word
amphibios, which means
“living a double life.”
The class Amphibia contains frogs and toads, salamanders and newts, and caecilians (long, legless burrowing
animals). The various species in this group are incredibly
diverse in shape and color, yet they make up the smallest class
of living vertebrates.
The amphibians usually have moist, glandular skin
that plays a vital role in respiration and water balance. The majority of these animals are
restricted to damp habitats and lay their jelly-like eggs in water. The eggs hatch into an
aquatic larval form and then metamorphose into the terrestrial adult.
Amphibians are ectothermic, which means that their body temperature is dependent on
their surroundings. Their world is a mosaic of warm and cool places, and by moving from one
to the other they can regulate their own body temperature. As seasonal temperatures decrease, so does the activity level of the amphibians. For this reason, these animals are most
abundant in the stable, warmer climates of the moist temperate and tropical regions.
OLD TERMS, NEW TERMS
Animals have long been described as “cold-blooded” or “warm blooded,” but these terms
are not correct. Amphibians and reptiles may increase their internal temperatures until
they are actually warmer than those of the "warm-blooded" birds and mammals. The
correct term for animals whose primary source of heat is external is ectothermic, while
those whose primary source of heat is internal are rightly called endothermic.
Salamanders and Newts
These small, wet-skinned amphibians have elongated bodies and long tails. They often
hide in shady, moist places during the day and become active at night. Living in a variety of
habitats, various species can be fully aquatic and use gills to breathe, fully terrestrial and have
developed lungs, or a combination of the two life-styles.
For the most part, salamanders tend to be terrestrial while newts are usually amphibious. Both types of amphibians lay their eggs in water or deposit them in moist places on land.
Adult and larval forms are carnivores, feeding on slugs, insects, snails and worms. Although
salamanders are not often seen, they are very abundant. In some mountain forests of North
America, it has been estimated that the total mass of woodland salamanders is larger than that
of all the birds and mammals together!
SHEDDING
The skin of salamanders and newts is smooth and flexible. The outermost layer is
periodically shed. Depending on the species, the skin may come off in small
patches or in one big piece. The animal usually eats the old skin, but sometimes a
whole salamander skin can be found hanging on a waterweed!
Frogs and Toads
Frogs and toads are the most numerous and diverse of the amphibians. The
approximate 3,500 species are found on most islands and every continent except Antarctica.
Although tropical rainforests hold the majority of these amphibians, deserts, swamps, savannas, and mountains are all colonized habitats.
Frogs are small, smooth-skinned
amphibians with short bodies and no tails. Their
long powerful hind limbs are used for jumping,
and the feet are often webbed for swimming. The
eyes are protected by moveable lids, and are
located, along with the nostrils, on the top of the
skull. This allows the animal to breathe and
watch its surroundings while the rest of the body
is submerged and hidden. The eardrums, or
tympanic membranes, are the large round spots
located behind the eyes.
Bullfrog
Toads are stout-bodied creatures with dry, warty skin. Some species have
specialized parotid glands located behind their eardrums that function as
poison glands. The toad can secrete an irritating, noxious poison from the
parotid glands that causes an attacker to spit the toad out and discourages
future feeding attempts on this unsavory creature.
Toads and frogs are most conspicuous during the breeding season. They
gather by the hundreds in ponds and streams and fill the evening air
with a chorus of clicks, peeps, bellows, and squawks. After the females
have selected suitable males of their own species, mating takes place.
The eggs are deposited in the water, where they eventually hatch into
tadpoles and then develop into frogs.
The round-bodied tadpoles breathe with external gills. They are “feeding machines,” consuming huge amounts of algae and water plants with
the help of specialized teeth made of keratin. Depending on the species,
the tadpole stage can last from a few days to several years.
As the tadpole matures, metamorphosis is dramatic. The larval teeth
are shed and the mouth widens. The limbs slowly appear and the fleshy
tail disappears. The gills are resorbed and the newly formed lungs take
over the breathing process. Internally, the digestive system changes
from the long gut required by the vegetarian diet to the much shorter
gut of the carnivore. The fully developed young frog then undergoes a
period of growth to become mature.
CREATIVE PARENTING
The eggs of frogs and toads are usually laid within the territory of the male and are
therefore defended by him. Some species, however, have developed some interesting
ways to care for their young. The midwife toad of Europe carries strings of eggs entwined around his hind legs, occasionally returning to the water to moisten them and
finally when they are ready to hatch. The males of species called "mouth-brooders"
actually carry as many as 20 growing tadpoles in their elongated vocal pouches! The
larvae of surinam toads develop in special "skin pockets" embedded in the adult
female's back. Perhaps one of the most bizarre examples of parental care in the amphibians is found in the Australian gastric-brooding frog. The female ingests about 20
fertilized eggs, which then develop in her digestive tract and are "vomited up" as tadpoles and froglets!
Reptiles
The class Reptilia contains over 6,500 species. Unlike the amphibians, these ectothermic
animals are not dependent on water for reproduction. The combination of leathery, shelled
eggs that prevent moisture loss, protective scaly skin,
and fully developed lungs enables the reptiles to live in
areas where amphibians cannot.
CREEPING CRAWLIES
The study of amphibians and
There are four major groups of reptiles found in
reptiles is called herpetology
the United States: turtles, snakes, lizards, and crocodil,from the Greek herpeton which
ians (alligators, crocodiles, gharials).
means “crawling things".
Turtles
Although different environmental conditions have led to a variety of alterations, the
protective shell is present in all turtles. Encasing this reptile’s body is the top shell, or carapace, the bottom shell, or plastron, and connective bridge extensions on either side. The complete shell is comprised of 59-61 bones. Large scales called scutes cover and strengthen the
bony shell. A turtle can feel pressure through its shell just as a person can feel something
pressing on their fingernail.
Several of the vertebrae and ribs are fused to the
turtle’s carapace, which means that unlike cartoon characters,
turtles cannot “come out” of their shell. This reptile’s shoulder
girdle has shifted to a location inside of the ribs, a characteristic found in no other vertebrate.
In some turtles, such as the softshells and sea turtles,
shell size has decreased, leaving spaces between the skeletal
bones called fontanelles. The advantages of less weight and
bulk are greater buoyancy and a lower energy cost for locomotion.
Carapace
Plastron
WHAT'S IN A GERMAN NAME?
The german word for turtle is
schildkrote, which translated literally means "armored toad!"
COMMON NAME CONFUSION!
The terms turtle, terrapin, sea turtle, and tortoise are easily confused, and often
have different meanings in different countries! In the United states, the following general definitions are accepted:
turtle - can refer to all species, but most often used to describe those that live
and feed in fresh water
tortoise - a terrestrial species; usually has a high, domed shell and club-like feet
terrapin - species that live and feed in brackish water
sea turtle - marine species
Snakes
The snakes are much like other reptiles in that they have scaly skin that they shed
throughout the year as they grow, are ectothermic, and often produce leathery eggs. The
limbless serpentine body has some unique adaptations that make the snake a highly specialized hunter that can move quickly, climb, burrow, and swim.
The human spine is composed of 33 vertebrae.
In comparison, snakes can have over 400 vertebrae, each connected to a pair of protective
ribs that curve around the internal
organs. The many vertebrae allow the
body to move sinuously, while the ribs,
scutes (belly scales), and muscles work
together to make the snake "slither."
Python
Snakes are carnivores, and
usually subdue their prey in one of two ways: they constrict it, or they inject it with venom. In
either case, the prey is consumed head first, and in one piece. The curved teeth act as hooks
that hold the quarry in place, while the snake moves the left and right sides of its jaw forward,
seemingly "walking" its mouth over the food. Since the jaws are loosely attached and the
bones that connect them are somewhat flexible, the snake can engulf prey that is larger than
the snake’s own head.
SNAKES AND PEOPLE
Snakes occupy an important ecological niche as part of the complex web of interrelationships in the natural world. They are often not well-liked by people, yet are beneficial in
many ways - including the fact that they keep the populations of crop damaging animals
in check. Most of the snakes in North America are harmless to humans. Of the nineteen
species in the U.S. that are potentially harmful, the majority are rattlesnakes and are
easy to identify because of the “rattlers” on the end of the tail. Other poisonous species
include the coral snake, cottonmouth, and the copperhead.
SNAKE SENSES
HEARING: Because snakes do not have external ears, they are deaf to
airborne sound. They can, however, feel the vibrations carried through
the ground, such as human footsteps on the forest floor.
HEAT SENSORS: Some snakes, such as the pit vipers, have heat sensitive pits between the scales of their “lips.” A snake can sense a change of
less than 0.002 degrees Fahrenheit, allowing it to accurately judge the
direction and distance of warm prey even in the dark.
EYESIGHT: The eyesight of snakes varies greatly from species to species. Some are nearly blind, while others have acute day and/or night
vision.
SMELL/TASTE: The information relayed by the snake's tongue tells the
animal a great deal about its environment. Each time the tongue flickers over a surface or in the air, it collects "smell/taste" molecules. The
tongue is then retracted, and the forked tip is inserted into the
Jacobson's organ in the roof of the mouth. It is within this organ that
the gathered chemical information is analyzed.
Lizards
Although the majority of the more than 3,700 species
of lizards inhabit tropical regions, these reptiles can be
found as far north as southern Canada and as far south as
the tip of Argentina. Most are land dwellers that are active
during the day.
Unlike their snake relatives, lizards have moveable eyelids and
external ear openings. They have the characteristic reptilian dry skin and usually have 4
short legs and clawed toes. Some lizards, like the chameleon, can hide from predators using
camouflage techniques. The speed and agility of other lizards are advantageous in eluding
predators, but if escape is impossible, some species have a unique method of defense - they
voluntarily shed their tail. The tail will continue to wiggle on its own for several minutes,
distracting the predator and allowing the lizard to escape unharmed. In time, the lizard is able
to regenerate a new tail.
Crocodilians
The alligators, crocodiles, and gharials are semi-aquatic reptiles with long bodies and
large, muscular tails covered with armor-like plates. The seven species in this family can be
found throughout the tropical and subtropical areas. Their body supports four limbs with the
front pair being much shorter than the hind pair. All four feet have “toes” and are slightly
webbed to provide a larger surface area for traction on land.
Most of the crocodilian's day may be spent hauled out on a bank basking, but by night
these reptiles are stealthy hunters. With legs folded back, the powerful tail propels the animal
silently through the water towards unsuspecting prey. Their eyes and nostrils are located on
the tip of their snout so that they can breathe and see while remaining almost totally submerged and hidden from view. Once the prey is captured in the crocodilian’s powerful jaws,
it is dragged underwater and consumed.
HOW ARE THEY DIFFERENT?
Alligators and crocodiles both live in North America. Although
similar in appearance, the two can be distinguished by the
width of their back and head and the position of the 4th mandibular tooth when the jaw is shut.
ALLIGATOR
The 4th tooth of the alligator's
lower jaw fits into a socket in the
upper jaw and cannot be seen when
the mouth is closed. The back and
head are wide.
Alligator
CROCODILE
The 4th tooth of the crocodile's lower
jaw is visible when the jaw is closed.
Its back and head are narrow when
viewed from above.
Crocodile
The largest of the living reptiles, the crocodilians are
found in a variety of habitats usually located near a water
source. They are quite agile in the water using their long
powerful tail to provide propulsion. When on land, the alligator must raise its body off the ground and walk with their legs
positioned underneath them. The faster they move, the more
they revert to the typical reptilian mode of splayed-leg belly
sliding. Most are unable to keep up speeds for very long with the
exception of the Johnston's crocodile which can gallop over short
distances to escape back to the water.
All crocodilians lay eggs, some as few as 10, others as many as 50. Alligators make
large mounds of vegetation, soil and other debris which function as nests. These nests provide
some protection for the eggs, but also functions as an incubator. The temperature inside the
nest is maintained by heat from the sun, heat from decaying vegetation, and metabolic heat
from the developing embryos. The temperature at which the embryos incubate determines
the sex of the offspring. Temperatures lower than 88OF (31OC) produce females while temperatures higher than 900F (320C) produce males. Intermediate temperatures produce both sexes.
Incubation lasts approximately 60-100 days depending on the species and the temperature.
Mammals
The mammals comprise approximately 4,500 species within 18 living orders. They are diverse in terms of size, shape, form and function. Mammals have certain characteristics that
set them apart from other living creatures. They are endothermic, they nourish their young
with milk secreted from mammary glands, their body is covered with hair, and they have
internal fertilization. Mammals live in a variety of habitats ranging from the most arid
desert to the coldest ocean. They have become adapted for survival in various
ways whether through camouflage, water regulation, feeding mechanisms, or
reproductive strategy.
Mammals may be classified as herbivores if they feed mainly on plants, carnivores if they feed mainly on herbivores or omnivores if they feed on both plants
and animals. Some are even considered insectivores such as shrews, moles and
anteaters. Mammals also exhibit three types of reproduction patterns. They
may be egg-laying mammals called monotremes, such as the duck-billed platypus, pouched
mammals called marsupials, such as the kangaroos, or placental mammals called eutherians,
such as the horse.
The Aquarium houses one species of mammal, the North American river otter. It can be
found in the Cove Forest exhibit.
Fish
Over half the vertebrates alive today belong to the
class Pisces. Grouped together in this class are three
separate categories: Agnatha (jawless fish),
Chondrichthyes (sharks, skates, rays, and chimaeras),
and Osteichthyes (bony fish). Of the approximately
21,000 species of living fishes, 97 percent are bony fishes.
WHAT IS A FISH?
No matter the shape, size, color,
or behavior, most fish share
basic characteristics: they have
a backbone, breathe with gills,
and move with fins.
Fish Shape
Fish come in every shape and size. Each shape, or form, reveals much about how and
where a fish lives. Although there are countless variations in shapes, most fish fit into one of
the following basic categories:
RIBBON-SHAPED
The eel has a long snakelike body that can negotiate seemingly inaccessible
crevices in search of food
and protection.
BOX-SHAPED
The box-shaped porcupine
fish can't move very quickly,
but it can hover and easily
maneuver in and around
reefs and mangrove roots.
TORPEDO-SHAPED
The body of the trout is stream-lined for
fast swimming, allowing it to move easily in
swift stream currents. Sharks and tuna are
also very sleek, stream-lined animals.
FLATTENED
The flattened shape of flounders and rays makes it nearly
impossible to see them as they lay on an ocean or river bottom.
They can effectively hide from predators - and their
unsuspecting prey!
COMPRESSED
Lookdowns and
angelfish are
animals that are
compressed from
side to side. They
are able to dart
quickly in and out
of reefs. When
viewed from the
front the fish is so
thin that it's
nearly invisible!
Fish Color
The colors and patterns of fishes are incredibly beautiful and intriguing to people - but
are often an important element in defense, reproduction, and survival for the fish.
Camouflage, or blending in with the environment, is essential for
some fish as they hide from predators or stalk prey. Fish that live in the
upper levels of open water, for example, are usually silvery so that
will be difficult to see in the sparkling water. Fish that live
among freshwater weeds are often mottled green and brown so
that they will blend with the murky shadows and vegetation. The
Mottled
brightly colored reef fish fade into the equally bright background of
Coloration
corals and sponges. Countershading is a type of coloration in which
the back of an animal is dark and the belly is light. When viewed from
above, the animals' back blends with the darker water below, and when viewed from underneath, the whitish belly blends with the lighter surface
waters. Countershading is an effective form of
camouflage used by many aquatic animals,
Countershading
including penguins, trout, killer whales, and
turtles. Disruptive coloration is used by fish
whose patterns and colors "break up" the outline of their bodies so
Disruptive
that they cannot be easily seen, such as filefish.
Coloration
Fish often have bright colors or distinctive patterns as a warning to other animals. The
tang is a tropical fish that has an bold outline of color around the scalpel-like blades on its tail.
The bright red and white stripes of the lionfish advertise the fact that its long spines are venomous. Many animals, including the sunfish and piranha, develop warning coloration when
they are guarding a nest or a mate. Fish such as the saltwater wrasse and the salmon develop
or intensify colors patterns to advertise for a mate.
Fish Senses
The senses of fish are quite different from that of humans. Many kinds of fishes have
excellent vision and well-developed senses of smell,
taste, and touch. Fish also have a latLateral Line
eral line, which is an important system for sensing vibrations and movement in the water. The lateral line
is a series of sensory cells that run the
length of the fish’s body. It helps the
fish travel through murky water, or even
travel at night. The lateral line also is an
important factor in keeping schooling fish in
a group and maneuvering as one unit.
Fish Fins
The appendages found on the body of a fish are called fins. Fins are usually
flexible, membranous structures which are supported by rays and spines. The two main
types are paired fins (one on each side of the body) and median, or unpaired, fins.
Median Fins
The anal and dorsal
fins act as keels to stabilize the fish in the water.
Median Fins
The caudal, or tail
fin along with the
muscular region,
called the caudal
peduncle, propels the
fish through the water.
Paired Fins
Pectoral and pelvic fins aid
in steering and manuvering.
The adipose fin is a soft, fleshy structure lacking rays or spines which is
located behind the dorsal fin in some
species of fish. The adipose fin serves no
apparent physiological purpose, but it is
a quick way to identify certain fish
families such as the trout and catfish.
Swim Bladder
Many species of fish are equipped with an internal
organ called a swim bladder that, along with the fins, helps the
fish maintain its position in the water. The gas-filled swim
bladder matches the fish's relative density to that of the water
surrounding it.
Another type of swim bladder is connected to the hearing
apparatus and is used to amplify sound. The freshwater drum is
equipped with this organ to create the drumming sound which is
associated with spawning activity.
The swim bladder of the bowfin is an example of the third
kind. This type of swim bladder is rich in blood vessels which absorb
oxygen from the air that is gulped at the surface. Fish with these
"auxillary breathing organs" are well suited to life in stagnant, lowoxygenated environments.
front
view
side
view
Buoyancy control
Sound
Auxiliary Breathing
Organ
Lateral Line
Close examination of most fish species reveals the presence of a line that runs the length
of the fish’s body. This is called the lateral line, and it is an intricate sensory organ that allows
a fish to detect temperature, pressure changes, and disturbances in water. It also enables a
fish to maintain orientation with its school as well as navigate at night.
VIBRATIONS
Pore
Skin
Inner Canal
Hairs
Embedded
in Jelly
Sensory Nerves
to Brain
Gills
HOW DOES IT WORK?
Sound vibrations are easily
carried through water and
enter the fish's lateral line
through tiny pores. The lateral line is a fluid-filled canal
under the skin that contains
sensitive hairs embedded in a
jelly mass. When the vibrations shake the hairs and the
little jelly lumps, the nerve
endings are stimulated and
nerve messages pass directly
to the brain.
Most animals on earth require oxygen to live. Fish use oxygen contained in water to
carry on the process of respiration. This is accomplished by use of special breathing organs
known as gills. When a gulp of water is taken into the fish’s mouth the operculum, or gill cover,
closes to prevent the water's escape. As water passes over the gills which are richly supplied
with blood vessels, oxygen is extracted. The oxygen passes through the gill membranes into
the fish’s blood stream. The operculum is then pushed open by the deoxygenated water, which
now contains carbon dioxide and other wastes, and the water exits the fish's body.
Caudal Fin
Caudal
Peduncle
Lateral
Line
Scales
Fin Spines
Pelvic Fin
Pectoral
Fin
FISH PARTS
Anal Fin
Second Dorsal Fin
First Dorsal Fin
Operculum
(Gill Cover)
Eye
Nostril