The ________ has a single opening that serves as both mouth and anus.
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Mollusks
________ are soft- bodied animals typically covered by a shell.
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Polychaetes
________ also differ from other annelids in having a well- defined head with sense organs.
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Chelicerates
________ have no antennae and no mandibles.
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Cnidarians
________ are characterized by radial symmetry, two tissue layers, and cnidocytes, cells containing stinging organelles called nematocysts.
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Hydrozoa
________ are typically polyps and may be solitary or colonial.
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Polyplacophorans
________ are chitons, mollusks with shells consisting of eight overlapping dorsal plates.
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Bivalves
________ are aquatic clams, scallops, and oysters.
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Parasitic leeches
________ are equipped with suckers for holding on to their host.
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Chelicerate body
The ________ consists of a cephalothorax and abdomen; there are six pairs of uniramous, jointed appendages, of which four pairs serve as legs.
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Decapod crustaceans
The ________ typically have five pairs of walking legs.
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Lophotrochozoa
The ________ make up a clade that includes some of the flatworms, nemerteans, mollusks, annelids, the lophophorate phyla, and rotifers.
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velvet worms
The arthropods along with the onychophorans (________) and tardigrades (water bears) make up the clade Panarthropoda.
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Poriferans
The ________, or sponges, are characterized by flagellate collar cells (choanocytes), which generate a water current that brings food and oxygen to the cells.
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Crustaceans
________ have two pairs of antennae that sense taste and touch, and a pair of mandibles used for chewing.
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life cycle
The ________ of many cnidarians includes a sessile polyp stage (a form with a dorsal mouth surrounded by tentacles) and a free- swimming medusa (jellyfish) stage.
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Nemerteans
________ have a complete digestive tract with mouth and anus, and a circulatory system.
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Scyphozoa
________ (jellyfish) are generally medusae.
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snails
The gastropods, which include the ________, slugs, and their relatives, have a well- developed head with tentacles.
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Arthropods
________ have an open circulatory system with a dorsal heart that pumps hemolymph.
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Insect
A(n) ________ is an articulated, tracheated hexapod; its body consists of head, thorax, and abdomen.
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Anthozoa
________ are polyps and may be solitary or colonial; anthozoans differ from hydrozoans in the organization of the gastrovascular cavity.
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Rotifers
________ are pseudocoelomates that are thought to have evolved from animals with a true coelom.
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tough cuticle
The body is covered by a(n) ________ that helps prevent desiccation.
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Leeches
________ belong to the group Hirudinida.
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setae
Oligochaetes, the group that includes the earthworms, are characterized by a few short ________ per segment.
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radula functions
A rasplike ________ as a scraper in feeding in all groups except the bivalves, which are filter feeders.
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Ecdysozoa
________ is one of the three major animal clades; its validity is based on many types of evidence, including molecular data.
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ganglia
The ________ are connected to two nerve cords that extend the length of the body.
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Ctenophores
________ have eight rows of cilia that resemble combs.
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hermaphrodites
Many flatworms are ________: a single animal produces both sperm and eggs.
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lophophore
The ________, a ciliated ring of tentacles surrounding the mouth, is specialized for capturing suspended particles in the water.
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Aquatic forms
________ have gills for gas exchange; terrestrial forms have either tracheae or book lungs.
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tentacles
They are diploblastic and have ________ with adhesive glue cells.
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sponge body
The ________ is a sac with tiny openings through which water enters; a central cavity, or spongocoel; and an open end, or osculum, through which water exits.
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Flatworms
________ have a ladder- type nervous system, typically consisting of sense organs and a simple brain composed of two ganglia.
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Collar cells
________ also trap and phagocytize food particles.
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coelom
The ________ can serve as a hydrostatic skeleton in which contracting muscles push against a tube of fluid.
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trilobites
The ________ are extinct marine arthropods covered by a hard, segmented shell.
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bilateral symmetry
The flatworms are acoelomate (have no coelom) animals with ________, cephalization, three definite tissue layers, and well- developed organs.
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true coelom
The ________ is a fluid- filled body cavity completely lined by mesoderm that lies between the digestive tube and the outer body wall.
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Annelids
________ have long bodies with segmentation both internally and externally; their large, compartmentalized coelom serves as a hydrostatic skeleton.
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extinct trilobites
Based on molecular and other data, arthropods are currently assigned to five main groups: ________ and extant Myriapoda, Chelicerata, Crustacea, and hexapoda.
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parasitic flukes
The ________ and tapeworms typically have suckers or hooks for holding on to their hosts; they have complicated life cycles with intermediate hosts and produce large numbers of eggs.
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Polychaetes
________ are marine annelids characterized by parapodia, appendages used for locomotion and gas exchange.
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Mollusks
________ have an open circulatory system except for cephalopods, which have a closed circulatory system.
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Crustaceans
________ vary greatly in the appearance and in the number of biramous appendages.
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Nemerteans
________ (ribbon worms) are characterized by the proboscis, a muscular tube used in capturing food and in defense.
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Arthropods
________ are segmented animals with paired, jointed appendages and an armorlike exoskeleton of chitin.
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lophophorates
The ________, marine animals that have a(n) ________, include the brachiopods, phoronids, and bryozoans.
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The coelom brings about the tube-within-a
tube body plan
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Many flatworms are hermaphrodites
a single animal produces both sperm and eggs
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Four groups of flatworms are recognized
class Turbellaria comprises free-living
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Based on molecular and other data, arthropods are currently assigned to five main groups
extinct trilobites and extant Myriapoda, Chelicerata, Crustacea, and hexapoda
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Each segment had a pair of biramous appendages, appendages with two jointed branches
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Flashcard (30)