Basis of classification of non chordata : symmetry, coelom, segmentation, embryogeny | bsc MGSU скачать в хорошем качестве

Basis of classification of non chordata : symmetry, coelom, segmentation, embryogeny | bsc MGSU

Basis of Classification of Invertebrates: Symmetry, Coelom, Segmentation, and Embryogeny These four characteristics are fundamental in classifying invertebrates. Let's break down each: Symmetry *Asymmetry:* No definite shape or pattern. Example: Sponges. *Radial symmetry:* Body parts arranged around a central axis. Example: Jellyfish. *Bilateral symmetry:* Body can be divided into two equal halves along a single plane. Example: Insects, humans. Coelom *Acoelomate:* No body cavity. Example: Flatworms. *Pseudocoelomate:* Body cavity partially lined with mesoderm. Example: Roundworms. *Coelomate:* Body cavity completely lined with mesoderm. Example: Earthworms, insects. Segmentation *Metamerism:* Body divided into segments with repeated structures. Example: Earthworms, insects. *No segmentation:* Body not divided into segments. Example: Jellyfish, flatworms. Embryogeny *Germ layers:* Number of tissue layers formed during embryonic development. Diploblastic: Two germ layers (ectoderm and endoderm). Example: Jellyfish. Triploblastic: Three germ layers (ectoderm, mesoderm, and endoderm). Example: Flatworms, insects. *Protostomes:* Blastopore develops into the mouth. Example: Mollusks, arthropods. *Deuterostomes:* Blastopore develops into the anus. Example: Echinoderms. [Image of germ layers and protostome vs. deuterostome development] Combined Classification These characteristics are often used in combination to classify invertebrates into different phyla. For example: *Phylum Porifera* (sponges): Asymmetrical, acoelomate, no segmentation, diploblastic. *Phylum Cnidaria* (jellyfish): Radial symmetry, acoelomate, no segmentation, diploblastic. *Phylum Platyhelminthes* (flatworms): Bilateral symmetry, acoelomate, no segmentation, triploblastic. *Phylum Annelida* (earthworms): Bilateral symmetry, coelomate, segmented, triploblastic. *Phylum Arthropoda* (insects, spiders): Bilateral symmetry, coelomate, segmented, triploblastic.