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STUDY GUIDE
Chapter 23 – Invertebrate Diversity
 Study for your test using your notes (from the SMART Board). The test is made directly
from those slides.
o Each slide contains important information – do not pick and choose what YOU
think is important.
 Study ALL of your vocabulary terms – they will all be on the test (in some way, shape,
or form).
Section 1
Section 2
Section 3
Section 4
Section 5
Section 6
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blastula
gastrula
larva
metamorphosis
invertebrate
vertebrate
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sponge
collar cell
amoebocyte
sessile
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spindle
cnidarian
radial
symmetry
cnidocyte
nematocyst
gastrovascular
cavity
polyp
medusa
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flatworm
bilateral
symmetry
roundworm
complete
digestive tract
 rotifer
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annelid
closed circulatory
system
 acoelomate
 pseudocoelom
 coelom
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Section 7
mollusk
mantle
radula
open circulatory
system
 gastropod
 bivalve
 cephalopod
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For the test, student should be able to:
 Identify the key terms listed above with the proper definitions (many parts of this test
are based on the vocabulary terms).
 Recognize the three possible types of symmetry and the details of each:
o Asymmetry
o Bilateral Symmetry
o Radial Symmetry
 List the four key characteristics of an animal.
 Recognize the differences between vertebrates and invertebrates and their
characteristics.
 Identify the basic characteristics of a sponge.
o Body structure  lack true tissues and organs, consists of two layers of cells
separated by a jelly-like material, two main cells (collar cells and ameobocytes), two
types of support (rigid and flexible).
o Diet  water moves into the sponge through the pores, food and oxygen is
filtered out of the water as it passes through, and water is then pushed out the
sponge up and out the top by the flagella of the collar cells.
o Reproduction  most common type of reproduction is a type of asexual
reproduction called budding – a piece of the sponge breaks off of the main
body, lands on the ocean floor, attaches itself in place, and grows into a full adult
sponge.
o Movement  sponges do not have the ability to move across the ocean floor,
making them sessile (remember though that movement is one of the characteristics that
is required of any living thing).
 Diagram of a
sponge from the text
-------------------------------------------------------------------------------------------------- Identify the basic characteristics of a cnidarian.
o Body structure  all cnidarians have tentacles with stinging cells and have
radial symmetry – all organisms with radial symmetry lack a head.
o Diet  a cnidarian captures its prey with its tentacles (like shown in the diagram
below) and pulls the food back to its mouth. Once food enters the
gastrovascular cavity, the food is digested and the wastes exit back out
through the mouth.
o Movement  most cnidarians are either slow-moving or sessile, and their
movement depends on their body forms:
 Medusa: move freely about in the water (jellyfish)
 Polyp: mostly sessile organisms (hydra)
o Examples  hydra, jellyfish
 Diagram of a
cnidarian from the text
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 Identify the basic characteristics of a flatworm.
o Body structure  have bilateral symmetry, a distinct head and a
distinct tail, and a flat-shaped body; simplest animals to have three tissue layers:
 Endoderm: most internal of the three layers; develops into the digestive sac
 Mesoderm: middle of the three layers; develops into the internal tissue-filled region
 Ectoderm: most external of the three layers; develops into the body covering
o Diet  when a flatworm is feeding, a muscular tube projects through the
mouth and sucks in food, similar to a vacuum; flatworms also have a
gastrovascular cavity, in which the food enters through one opening, the
food is digested, and the wastes exit back out of the same opening.
o Sensitivity  they are aware of their surroundings in two different ways:
 The pair of eyespots that detect light.
 The side flaps that function mainly for smell.
o Movement  flatworms can move in several ways:
 They use cilia on its ventral surface to slide about in search for
food.
 They have muscles that enable it to twist and turn.
o Examples  planarians, tapeworm
 Diagram of a
flatworm from the text
-------------------------------------------------------------------------------------------------- Identify the basic characteristics of a roundworm.
o Body structure  also has three tissue layers (endoderm, mesoderm,
ectoderm)
o Diet  presence of a complete digestive tract, in which there are two openings
instead of just one – a mouth and an anus, and a digestive tube connecting
them to each other.
o Examples  hookworms, pinworms, threadworms
-------------------------------------------------------------------------------------------------- Identify the basic characteristics of an annelid.
o Body structure  have a closed circulatory system in which the blood stays
contained in vessels and does not come in direct contact with the tissues and
organs.
o Habitat  they live in any moist environment (anywhere except dry sand
or frozen soil) – this is due to the way they breathe. Oxygen is absorbed through
their skin, similarly to how lotion absorbs into the skin of a human.
o Reproduction  they are hermaphrodites that cannot reproduce on their
own – they need another annelid to exchange sperm with. When reproduction
happens, two annelids both reproduce at the same time with each other.
o Movement  have segmented bodies, that each contain their own set of
muscles that expand and contract to allow movement; they also have bristles
called setae on their bellies that aid in their movement through soil.
o Examples  earthworm, sandworm
 Diagram of an
annelid from the text
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 Identify the basic characteristics of a mollusk.
o Body structure  all mollusks have a foot and a mantle – the foot aids in
locomotion and the mantle covers the body and secretes (creates) the shell; most
mollusks have an open circulatory system that includes a heart that pumps
blood into vessels.
THREE TYPES OF MOLLUSKS:
GASTROPOD
o Body structure  most organisms in this class have a single shell that is often
spiral-shaped.
o Examples  land slugs and snails
BIVALVE
o Body structure  have hinged shells divided into two halves; the prefix bitranslates to the word two, and the root -valve translates to the term shell.
o Diet  feed by pumping water over their gills and trapping food particles that
are suspended in water.
o Examples  clam, oyster, mussel
CEPHALOPOD
o Body structure  in most, the shell is small and internal or missing altogether.
o Diet  use beak-like jaws and a radula to crush or rip prey apart; their mouth
is at the center of their foot, which is surrounded by 8-10 inch long tentacle-like
arms that catch and hold prey.
o Movement  move through the water by jet propulsion (pull water into
their bodies and then push the water out in order to push their bodies forward).
o Examples  squid, octopus