Key Points
Key Points: Kingdom Animalia
- Meaning - Heterotrophic, multicellular eukaryotes; cells lack a cell wall; cannot produce their own food.
- Nutrition - Mode of nutrition is holozoic (food obtained by ingestion); food is digested in an internal cavity; food is stored as glycogen or fat.
- Reproduction - By sexual reproduction - copulation of male and female followed by embryological development.
- Other features - Follow a definite growth pattern; higher forms have elaborate sensory and neuromotor mechanisms (nervous system and sensory organs); most are capable of locomotion.
- Cell structure - Has a nucleus and membrane-bound organelles; no chloroplasts (hence cannot photosynthesise); no cell wall (unlike plants and fungi).
Key Points: Classification of Kingdom Animalia
- The animal kingdom is classified based on level of organisation, symmetry, and body cavity.
- Cellular-level organisms are asymmetrical and belong to Porifera.
- Tissue-level organisms show radial symmetry and include Cnidaria and Ctenophora.
- Organ/organ system level organisms show bilateral symmetry and are further classified based on the body cavity.
- Based on body cavity:
Acoelomates → Platyhelminthes,
Pseudocoelomates → Aschelminthes,
Coelomates → Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, Chordata.
Key Points: Class Chondrichthyes
- Chondrichthyes are marine fishes with a cartilaginous skeleton and streamlined bodies.
- They have a ventral mouth, separate gill slits, and no operculum.
- Skin has placoid scales, modified as teeth; no air bladder is present.
- They are cold-blooded with a two-chambered heart; some have electric organs or poison stings.
- Sexes are separate, fertilisation is internal, and many are viviparous.
- Examples: Scoliodon, Pristis, Carcharodon, Trygon.
Key Points: Class Osteichthyes
- Osteichthyes are bony fishes found in both marine and freshwater habitats.
- They have a bony endoskeleton, a terminal mouth, and gills covered by an operculum.
- Skin has cycloid or ctenoid scales and an air bladder for buoyancy.
- They are cold-blooded with a two-chambered heart and separate sexes.
- Fertilisation is mostly external and they are oviparous.
- Examples: Labeo, Catla, Exocoetus, Hippocampus.
