Invertebrates do not have a backbone or a spinal cord. Invertebrates can be found in many different phyla, including porifera (sponges), which are filter feeders who have mobile amoebocyte cells as well as choanocytes or collar cells. They can reproduce asexually (via fragmentation), or sexually (via external fertilization). Cnidaria includes jellyfish, corals, and sea anemones, which have a nerve net but not a central nervous system. Platyhelminthes (flatworms) are bilaterally symmetrical and have a head end with a high concentration of sensory organs (cephalization). Rotifers (microscopic aquatic animals), nemotodes, annelids (earthworms), molluscs, arthropods (many insects and crabs), and echinodermata (sea stars) are all also important invertebrates.
Invertebrates are animals that
lack a backbone and spinal cord.
Major phyla of invertebrates
Porifera – Sponges are
sessile filter feeders that do not have a symmetrical body plan and
lack specialized tissues and organs.
Cnidaria - Includes jellies,
hydra, corals and sea anemones. Cnidaria have true tissues and
either polyp or medusa body plans. Their nervous system is composed
of a nerve net.
Platyhelminthes - Flatworms
have body plans that exhibit bilateral symmetry and cephalization.
Rotifera - Rotifers are
microscopic aquatic animals. They are filter feeders with a
pseudocoelem and a complete digestive tract.
Nematoda - Roundworms are
unsegmented worms with a complete GI tract.
Annelida - Annelids are
segmented worms such as earthworms and leeches. They have a ceolom
and a closed circulatory system as well as a complete GI tract.
Mollusca - Molluscs include
octopuses, chitons, squids, snails, slugs and clams. Molluscs have a
head-foot region, a visceral mass and a mantle.
Arthropoda - Arthropoda is the
largest phylum. Its members have segmented bodies with three
regions, a head, thorax and abdomen. They have an exoskeleton and
Echinodermata -Sea stars, sea
urchins and sand dollars are echinoderms. Members of this phylum are
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The book and CD package include two full length practice exams that are presented with all questions answered and explained. The author also presents detailed reviews of all test topics and includes multiple-choice and free-response questions with answers at the end of each topic's chapter.
This book includes a review of the AP Biology exam format and scoring, proven strategies for answering multiple-choice questions, and hints for tackling the essay questions. The practice tests include answers and explanations and there is also proven test-taking strategies for both the multiple choice and essay parts.