SSC CGL Biology · Biodiversity and Classification
Animal Kingdom Classification
The animal phyla from sponges to arthropods with their marks and examples, and the vertebrate classes: which are warm-blooded, which lay eggs, and the genus names SSC uses.
Why this matters
Twenty-six questions in the bank: 14 from the 2023 shifts and 12 from the 2024 shifts. Nearly every one gives a genus name (Obelia, Ascaris, Pteropus) and asks its group, so the example columns are what to learn.
Concept 1 of 3: Sponges, cnidarians and worms
Definition
The phyla:
- Porifera (sponges: Sycon, Spongilla, Euplectella): cellular grade of organisation.
- Cnidaria or Coelenterata (Hydra, jellyfish, sea anemone Adamsia, brain coral Meandrina): radial symmetry, cell-tissue grade. Obelia shows metagenesis, a polyp stage alternating with a medusa stage.
- Ctenophora (Pleurobrachia, Ctenoplana): marine comb jellies.
- Platyhelminthes (flatworms: tapeworm Taenia, liver fluke): bilateral, three-layered, no coelom, no anus; flame cells for osmoregulation. Many are endoparasites.
- Aschelminthes (roundworms: Ascaris): a complete gut with a muscular pharynx. Ancylostoma is the hookworm, Wuchereria the filarial worm; the pinworm is Enterobius.
Protists such as Paramecium are at the protoplasmic grade.
Practise this conceptself-check · 3 quick reps
The same idea in a real exam question:
Example 1 · Biodiversity and Classification · Animal Kingdom Classification
Euplectella is a sponge
Concept 2 of 3: Annelids, arthropods, molluscs and echinoderms
Definition
The phyla:
- Annelida (earthworm, leech Hirudinaria, Nereis): ring segments; move with setae or parapodia.
- Arthropoda: jointed legs and an exoskeleton of chitin (not lignin); body in head, thorax and abdomen. The largest phylum, over 85% of known animals; insects are its largest class. Subphyla: Hexapoda (mosquito, butterfly, ant), Crustacea (Daphnia, crayfish), Myriapoda (Julus, a millipede), Chelicerata (Limulus, the king crab).
- Mollusca (Pila, octopus or devil fish): soft body, often a shell. Pinctada margaritifera is the black-lip pearl oyster.
- Echinodermata (sea star): spiny skin.
Practise this conceptself-check · 3 quick reps
The same idea in a real exam question:
Example 2 · Biodiversity and Classification · Animal Kingdom Classification
Chitin, not lignin
Concept 3 of 3: Reptiles, birds and mammals
Definition
The classes:
- Reptilia (turtles, chameleon, snakes): cold-blooded, scaly, eggs on land. Typhlops is the blind snake.
- Aves (birds): warm-blooded, four-chambered heart, lungs, all lay eggs, pneumatic bones. Genera: Psittacula (parakeet), Struthio (ostrich), Neophron (vulture), Pavo (peacock).
- Mammalia: warm-blooded; most give birth to live young. Pteropus, the flying fox, is a bat, so a mammal. Macropus is the kangaroo.
The gaur (Indian bison) is the closest wild relative of domestic cattle, seen in Nagarhole and Bandipur.
Practise this conceptself-check · 3 quick reps
The same idea in a real exam question:
Example 3 · Biodiversity and Classification · Animal Kingdom Classification
No bird gives birth to live young
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Reference tables (3)
Watch out for (3)
- Euplectella is a sponge→ Sponges, cnidarians and worms
- Chitin, not lignin→ Annelids, arthropods, molluscs and echinoderms
- No bird gives birth to live young→ Reptiles, birds and mammals
Test yourself on Biodiversity and Classification
15 past SSC CGL questions from this chapter, timed at 9 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.