Porifera & Coelenterata – The Simplest Animals
These are the two simplest phyla of multicellular animals (Kingdom Animalia)
Both are aquatic, mostly marine, and show very primitive organization
Both are aquatic, mostly marine, and show very primitive organization
- Porifera – Sponges
- Coelenterata (Cnidaria) – Jellyfish, corals, hydra
Porifera vs Coelenterata – Comparison
| Feature | Porifera (Sponges) | Coelenterata (Cnidaria) |
|---|---|---|
| Level of organization | Cellular level | Tissue level |
| Body symmetry | Asymmetrical / none | Radial symmetry |
| True tissues | Absent | Present (diploblastic) |
| Body cavity / coelom | Absent (only spongocoel) | Gastrovascular cavity |
| Digestive system | Intracellular digestion | Extracellular + intracellular |
| Special cells | Choanocytes (collar cells) | Cnidocytes / nematocysts |
| Nervous system | Absent | Primitive nerve net |
| Examples | Sycon, Spongilla, Euplectella | Hydra, Jellyfish, Coral, Sea anemone |
3. Phylum Porifera
Simplest multicellular animals – "pore bearers"
- Porous body
- Flagellated collar cells
- Spicule / spongin skeleton
- Intracellular digestion
- Aquatic, mostly marine
🧽 Sycon Anatomy - Interactive Learning
Sycon Structure
📚 Structure Information
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4. Phylum Coelenterata (Cnidaria)
Tissue level organization – first animals with definite tissues
- Stinging cells
- Polyp & Medusa forms
- Gastrovascular cavity
- Two germ layers
- Diffuse nervous system
🪸 Cnidaria Anatomy - Interactive Learning
Cnidaria Structure (Polyp form)
📚 Structure Information
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