Invertebrate Zoology Lecture Notes Ppt New Jun 2026

: Sea cucumbers featuring elongated fleshy bodies.

Echinoderms are coelomate deuterostomes, making them more closely related to chordates than any other major invertebrate phylum. Key Anatomical Characteristics

Provided by spicules (calcium or silica) and spongin fibers. 3. Phylum Cnidaria: The Stingers

[ Asconoid ] ---> [ Syconoid ] ---> [ Leuconoid ] (Simplest wall) (Folded walls) (Complex chambers) : Simple vascular tube with pore channels. Syconoid : Tubular body with folded walls. Leuconoid : Most complex with clustered water chambers. Cell Types Pinacocytes : Form the outer protective layer. Choanocytes : Flagellated cells generating water currents. Amoebocytes : Distribute nutrients and secrete skeleton. Skeletal Structures Spicules : Calcium carbonate or silica structures. Spongin : Collagen protein network providing flexibility. Module 3: Phylum Cnidaria General Characteristics Radial symmetry. Tissue level of organization. Diploblastic body plan. Gastrovascular cavity with single opening. Dimorphic Life Cycle Polyp : Hydroid form adapted to sessile life. Medusa : Jellyfish form adapted to free-swimming. Specialized Stinging Cells Cnidocytes : Specialized cells used for defense and hunting. invertebrate zoology lecture notes ppt new

Choanocytes (Collar Cells) : Flagellated cells that drive water currents and trap food particles.

Invertebrate Zoology: Evolutionary Trends & Taxonomical Overview

No fluid-filled body cavity exists between the gut and the outer body wall. The space is entirely filled with mesodermal parenchyma tissue (e.g., Platyhelminthes). : Sea cucumbers featuring elongated fleshy bodies

Acoelomate body plan, cephalization, excretion via protonephridia, and parasitic adaptations (flukes and tapeworms).

A tissue drape over the visceral mass. It secretes the calcium carbonate shell and protects the gill cavity.

Radula , a rasping, tongue-like organ (absent in bivalves). Major Classes: Leuconoid : Most complex with clustered water chambers

Made of calcium-rich plates called ossicles. Located just beneath the skin.

Especially for parasites (Platyhelminthes) and Cnidarians.