Animal Kingdom flash cards

1. 1.On what two bases is animal classification broadly done?

   On the basis of common fundamental features (body plan, symmetry, organisation, etc.) — arrangement of body cells, and evolutionary relationships, independent of habit or habitat.

   Hint: fundamental features, not habitat

2. 2.Name the levels (grades) of body organisation in animals, simplest to complex.

   Cellular level (Porifera) → Tissue level (Coelenterata/Ctenophora) → Organ level (Platyhelminthes onwards) → Organ-system level (Nematoda onwards / higher).

   Hint: cell → tissue → organ → organ-system

3. 3.Which phylum shows cellular level of organisation?

   Porifera — cells are arranged as loose aggregates and perform division of labour, but no tissues.

   Hint: sponges, loose cell aggregates

4. 4.Which two phyla show tissue level of organisation?

   Coelenterata (Cnidaria) and Ctenophora.

   Hint: diploblastic, tissue grade

5. 5.From which phylum does organ-system level of organisation begin?

   Organ-system level is well shown from Nematoda/Aschelminthes and higher; in these systems can be of open or closed type (e.g. circulatory).

   Hint: systems appear in higher phyla

6. 6.Define asymmetry with an example.

   Body cannot be divided into two equal halves by any plane passing through the centre. Example: adult Sponges (many).

   Hint: no plane gives equal halves

7. 7.Define radial symmetry with examples.

   Any plane passing through the central axis divides the body into two identical halves. Examples: Coelenterates, Ctenophores, adult echinoderms.

   Hint: like a wheel — any central plane

8. 8.Define bilateral symmetry with examples.

   The body can be divided into identical left and right halves by only one plane. Examples: Annelids, Arthropods, and most higher animals.

   Hint: one plane, left = right

9. 9.Which phylum shows radial symmetry in adults but bilateral in larvae?

   Echinodermata — larvae are bilaterally symmetrical; adults become radially (pentamerous) symmetrical.

   Hint: starfish adult vs its larva

10. 10.Define diploblastic animals with an example.

    Animals with cells arranged in two embryonic germ layers — external ectoderm and internal endoderm — with an undifferentiated mesoglea in between. Example: Coelenterates.

    Hint: two layers + mesoglea

11. 11.Define triploblastic animals.

    Animals with three germ layers — ectoderm, mesoderm and endoderm. Seen from Platyhelminthes to Chordates.

    Hint: ecto + meso + endo

12. 12.What is mesoglea?

    The undifferentiated, non-cellular gelatinous layer present between ectoderm and endoderm in diploblastic animals.

    Hint: jelly between two layers

13. 13.Define coelom.

    A body cavity lined by mesoderm (mesodermal epithelium).

    Hint: mesoderm-lined cavity

14. 14.Define coelomate animals with examples.

    Animals possessing a true coelom lined by mesoderm on both sides. Examples: Annelids, Molluscs, Arthropods, Echinoderms, Hemichordates and Chordates.

    Hint: true mesoderm-lined cavity

15. 15.Define pseudocoelomate animals with an example.

    Body cavity is not lined by mesoderm; instead mesoderm is present as scattered pouches between ectoderm and endoderm. Example: Aschelminthes (Nematoda).

    Hint: false coelom, scattered mesoderm

16. 16.Define acoelomate animals with an example.

    Animals in which the body cavity is absent. Example: Platyhelminthes.

    Hint: no body cavity — flatworms

17. 17.QUESTION: Arrange by coelom — Ascaris, Fasciola, Earthworm. Which is acoelomate, pseudocoelomate, coelomate?

    Fasciola (Platyhelminthes) = acoelomate; Ascaris (Aschelminthes) = pseudocoelomate; Earthworm (Annelida) = coelomate.

    Hint: flatworm, roundworm, segmented worm

18. 18.Define metamerism (segmentation) with an example.

    Body is externally and internally divided into serially repeated segments (metameres) with linear repetition of organs. Example: Earthworm (Annelida).

    Hint: true serial segmentation — annelids

19. 19.What is a notochord and when does it appear?

    A flexible rod-like structure formed on the dorsal side during embryonic development. Animals having it are chordates; those without are non-chordates.

    Hint: dorsal rod, chordate hallmark

20. 20.Give the general characters of Phylum Porifera.

    Sponges; mostly marine, asymmetrical, cellular level; sessile; have water transport (canal) system; body with pores (ostia) and osculum; skeleton of spicules/spongin fibres; choanocytes (collar cells) line spongocoel; hermaphrodite; indirect development.

    Hint: sponges with pores and canal system

21. 21.What is the function of the water canal (transport) system in sponges?

    Water enters through ostia into the central cavity (spongocoel) and leaves via the osculum; it helps in food gathering, respiratory exchange and removal of waste.

    Hint: ostia → spongocoel → osculum

22. 22.What are choanocytes?

    Collar cells lining the spongocoel and canals of sponges; they help maintain the water current and in nutrition.

    Hint: collar cells of sponges

23. 23.Give examples of Phylum Porifera.

    Sycon (Scypha), Spongilla (freshwater sponge), Euspongia (bath sponge).

    Hint: Sycon, Spongilla, Euspongia

24. 24.Give the general characters of Phylum Coelenterata (Cnidaria).

    Aquatic, mostly marine; radial symmetry; diploblastic, tissue level; have cnidoblasts (stinging cells) on tentacles/body for defence, anchorage and capturing prey; central gastrovascular cavity with single opening (hypostome); polyp and medusa forms; some form coral reefs.

    Hint: cnidoblasts + gastrovascular cavity

25. 25.What are cnidoblasts and where are they found?

    Stinging cells (containing nematocysts) present on the tentacles and body of Cnidarians; used for anchorage, defence and capturing prey — the feature that names the phylum Cnidaria.

    Hint: stinging cells of cnidarians

26. 26.Explain the two body forms (polymorphism) in Cnidaria.

    Polyp — sessile, cylindrical form (e.g. Hydra, Adamsia). Medusa — free-swimming, umbrella-shaped form (e.g. Aurelia, jellyfish). Forms with both show alternation of generations (metagenesis): polyps produce medusae asexually, medusae form polyps sexually.

    Hint: polyp (sessile) vs medusa (free)

27. 27.What is metagenesis in Cnidaria?

    Alternation of generations — polyps produce medusae asexually and medusae produce polyps sexually (e.g. Obelia).

    Hint: polyp asexual, medusa sexual

28. 28.Give examples of Phylum Coelenterata.

    Physalia (Portuguese man-of-war), Adamsia (sea anemone), Pennatula (sea-pen), Gorgonia (sea-fan), Meandrina (brain coral); Aurelia and Hydra.

    Hint: corals, sea anemone, Hydra

29. 29.Give the general characters of Phylum Ctenophora.

    Exclusively marine; radially symmetrical; diploblastic, tissue level; body with eight external rows of ciliated comb plates (used in locomotion); bioluminescent; hermaphrodite; only sexual reproduction; indirect development.

    Hint: comb jellies, 8 comb-plate rows

30. 30.What is special about locomotion and light in Ctenophores?

    Locomotion by eight rows of ciliated comb plates; they show bioluminescence (ability to emit light).

    Hint: comb plates + glow

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