Chapter 26: Sponges, Cnidarians, and Unsegmented Worms
Section 1: Introduction to the Animal Kingdom
Introduction to the Animal Kingdom
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The _________________________________________________ is the most
diverse in form
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Each animal performs the essential functions of life in its own special way
•
Two divisions that we will use to separate the animal kingdom are
vertebrates and invertebrates
– ____________________________________ have a backbone
– ____________________________________ have no backbone
What Is an Animal?
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All animals share certain basic characteristics
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Animals are ________________________________________ (they do NOT
make their own food)
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Instead, they obtain the nutrients and energy they need by feeding on
organic compounds that have been made by other organisms
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Animals are __________________________________, which means that their
bodies are composed of more than one cell
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Animal cells are also ___________________________________ – they contain a
nucleus and membrane-enclosed organelles
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An animal is a multicellular eukaryotic heterotroph whose cells lack
cell walls
Cell Specialization and Division of Labor
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The bodies of animals contain many types of specialized cells
•
Each specialized cell has a ___________________, ________________________
_____________________________, and ___________________________________
_____________________________ that make it uniquely suited to perform a
particular function within a multicellular organism
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For this reason, groups of specialized cells carry out different tasks for the
organism – ________________________________________
What Animals Must Do to Survive
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In order to survive, animals must be able to perform a number of essential
functions
•
For each animal group we study in the next several chapters, we will
examine these functions and describe the cells, tissues, organs, and organ
systems that perform them
Feeding
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Animals have evolved a variety of ways to feed
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____________________________ eat plants
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____________________________ eat animals
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____________________________ live and feed either inside or attached to
outer surfaces of other organisms, causing harm to the host
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________________________________________ strain tiny floating plants and
animals from the water around them
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________________________________________ feed on tiny bits of decaying
plants and animals
Respiration
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Living cells consume _____________________________ and give off
________________________________________ in the process of cellular
respiration
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Entire animals must respire, or breathe, in order to take in and give off
these gases
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Small animals that live in water or in moist soil may respire through their
_________________
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For large active animals, however, respiration through the skin is not
efficient
•
The _______________________________________________ these animals have
evolved take many different forms in adaptations suited to different habitats
Internal Transport
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Some aquatic animals can function without an internal transport system
•
But once an animal reaches a certain size, it must somehow carry
______________________, _______________________________, and
____________________________________________ to and from cells deep
within its body
•
Many multicellular animals have evolved a ______________________________
____________________________ in which a pumping organ called a
____________________ forces a fluid called ______________________ through
a series of ____________________________________
Excretion
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Cellular metabolism produces chemical wastes such as
____________________________ that are harmful and must be eliminated
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Small aquatic animals depend on ____________________________ to carry
wastes from their tissues into the surrounding water
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But larger animals, both in water and on land, must work to remove
poisonous metabolic wastes
Response
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Animals must keep watch on their surroundings to find food, spot
predators, and identify others of their own kind
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To do this, animals use specialized cells called _________________________,
which hook up together to form a ______________________________________
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________________________________________, such as eyes and ears, gather
information from the environment by responding to light, sound,
temperature, and other stimuli
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The ___________________, which is the nervous system’s control center,
processes the information and regulates how the animal responds
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The complexity of the nervous system varies greatly in animals
Movement
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Some animals are ______________________________, which means that they
live their entire adult lives attached to one spot
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But many animals are _________________________, which means that they
move around
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To move, most animals use tissues called muscles that generate force by
contracting
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In the most successful groups of animals, muscles work together with a
skeleton, or the system of solid support in the body
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Insects and their relatives wear their skeletons on the outside of their
bodies
– _________________________________
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Reptiles, birds, and mammals have their skeletons inside their bodies
– ___________________________________
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We call the combination of an animal’s muscles and skeleton its musculo –
skeletal system
Reproduction
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Animals must reproduce or their species will not survive
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Some animals switch back and forth between asexual and sexual
reproduction
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Many animals that reproduce sexually bear their young __________________
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Others __________________________
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The eggs of some species hatch into baby animals that look just like
miniature adults
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These baby animals increase in size but do not change their overall form
– ________________________________________
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In other species, eggs hatch into __________________________, which are
immature stages that look and act nothing like the adults
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As larvae grow, they undergo a process called
_______________________________________ in which they change shape
dramatically
– _____________________________________________
Trends in Animal Evolution
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The levels of organization become higher as animals become more
complex in form
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The essential functions of less complex animals are carried out on the cell
or tissue level of organization
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As you move on to more complex animals, you will observe a steady
increase in the number of _____________________________________________
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You will also see those tissues joining together to form more and more
specialized organs and organ systems
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Some of the simplest animals have radial symmetry; most complex
animals have bilateral symmetry
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Some of the simplest animals have body parts that repeat around an
imaginary line drawn through the center of their body
– ______________________________________
• Animals with radial symmetry never have any kind of real “head”
• Many of them are sessile, although some drift or move in a random
pattern
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Most complex invertebrates and all vertebrates have body parts that repeat
on either side of an imaginary line drawn down the middle of their body
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One side of the body is a ___________________________________ of the other
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These animals are said to have _________________________________________
– Animals with bilateral symmetry have specialized front and back ends as
well as upper and lower sides
• _______________________ = front end
• _______________________ = back end
• _______________________ = upper side
• _______________________ = lower side
•
More complex animals tend to have a concentration of sense organs
and nerve cells in their anterior (head) end
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This gathering of sense organs and nerve cells into the head region is
called ______________________________________
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Nerve cells in the head gather into clusters that process the information
gathered by the nervous system and control responses to stimuli
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Small clusters of nerve cells are called ________________________
– In the most complex animals, large numbers of nerve cells gather
together to form larger structures called ____________________