Invertebrates️️Animals without a backbone. About 95% of known animal species.
Calcarea and Silicea️️phylum that includes sponges; no symmetry, tissues, body cavity,
organs, nervous system; basal animals; mostly marine; contain spicules; most are
hermaphrodites; free-swimming during larva...
Campbell Biology Chapter 33 Invertebrates
with refined Questions and Answers
2024/2025
Invertebrates✔️✔️Animals without a backbone. About 95% of known animal species.
Calcarea and Silicea✔️✔️phylum that includes sponges; no symmetry, tissues, body cavity,
organs, nervous system; basal animals; mostly marine; contain spicules; most are
hermaphrodites; free-swimming during larval stage and sessile (non motile) as adults;
suspension/filter feeders
Suspention feeders✔️✔️small and large organisms that use filtering and trapping techniques to
collect minute food particles suspended in the water
Spongocoel✔️✔️large central cavity of the sponge
Osculum✔️✔️A large opening on a sponge through which filtered water is expelled
Choanocytes✔️✔️specialized cell in sponges that uses a flagellum to move a steady current of
water through the sponge
mesohyl✔️✔️a gelatinous region between the two layers of cells of a sponge
amoebocytes✔️✔️the "do-all" cells of sponges, moving by means of pseudopodia, they digest and
distribute food, transport oxygen, and disposes of waste. they manufacture the fibers that make
up a sponges skeleton
Eumetazoa✔️✔️Members of the subkingdom that includes all animals except sponges. (true
tissues)
Cnidaria✔️✔️animal phylum characterized by having diploblastic tentacled polyp and/or medusa
(jelly) body forms with radial symmetry; tentacles bear cells called cnidocytes that have weapons
called cnidae (e.g., stinging barbs called nematocysts). Gastrovascular cavity with a single
opening. - corals, jellies and hydras
gastrovascular cavity✔️✔️digestive chamber with a single opening, in which cnidarians,
flatworms, and echinoderms digest food
Polyps✔️✔️The sessile variant of the cnidarian body plan. The alternate form is the medusa.
Cylindrical forms that adhere to the substrate by the aboral end of their body, waiting for the
prey. - hydras
, Medusa✔️✔️The floating, flattened, mouth-down version of the cnidarian body plan. The alternate
form is the polyp.
Cnidocytes✔️✔️a specialized cell for which the phylum Cnidaria is named; consists of a capsule
containing a fine coiled thread, which, when discharged, functions in defense and prey capture
Nematocytsts✔️✔️a type of cnidocyte that has a long filament coiled up inside it and can penetrate
the prey.
4 major classes of phylum Cnidaria✔️✔️Hydrozoa, Scyphozoa, Cubozoa, Anthozoa
Hydrozoans✔️✔️A class of Cnidaria where most of the organisms alternate between polyp and
medusa except hydras, which are only polyp. They can reproduce both asexually and sexually.
Scyphozoans✔️✔️Group of cnidarians,all marine, polyp stage is greatly reduced, free swimming
medusae is up to 2 m in diameter. (Jellies,sea nettles)
Cubozoans✔️✔️Class of Cnidaria with a box-shaped medusa stage and complex eyes. Often
equipped with toxic cnidocytes.
Anthozoans✔️✔️class of cnidarian; sea anemones and corals occurring only as polyps. Corals
excrete an exoskeleton of calcium carbonate, form symbioses with algae.
Lophotrochozoans✔️✔️Member of a group of animal phyla identified as a clade by molecular
evidence. Lophotrochozoans include organisms that have lophophores or trochophore larvae.
Includes about 18 phyla - introduced 6 are flatworms, rotifers, ectoprocts, brachiopods, molluscs
and annelids.
Bilateria✔️✔️A member of a major lineage of animals (Bilateria) that are bilaterally symmetrical
at some point in their life cycle, have three embryonic germ layers, and have digestive tract with
two opening and a coelom. All protostomes and deuterostomes are bilaterians.
3 major clades of Bilateria✔️✔️1. lophotrochozoa
2. ecdysozoa
3. deuterostomia
lophophore✔️✔️In some lophotrochozoan animals, including brachiopods, a crown of ciliated
tentacles that surround the mouth and function in feeding.
trochophore larva✔️✔️Distinctive larval stage observed in some lophotrochozoan animals,
including some annelids and molluscs.
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