Govt Exams
While both have amniotic eggs, only mammals possess a diaphragm and mammary glands. Mammals have two occipital condyles, and are endothermic.
The notochord arises from the chordamesoderm (axial mesoderm) derived from the primitive streak during early development.
The water vascular system and tube feet are unique to Echinodermata. Despite radial adult symmetry, echinoderms have bilateral larvae, indicating deuterostome origin.
All three adaptations—keratinized skin, shelled eggs, and scales—collectively reduce water loss in reptiles while maintaining respiration and reproduction efficiency.
The notochord and dorsal neural tube are fundamental chordate features appearing first in fish and retained throughout vertebrate evolution.
Axolotl (a salamander) exhibits neoteny, retaining larval characteristics (external gills) throughout its life even after sexual maturity.
The presence of cnidocytes (stinging cells), radial symmetry, and gastrovascular cavity are defining characteristics of Cnidaria (corals, jellyfish, hydra).
While Annelida and Arthropoda both show segmentation, Mollusca lacks true segmentation. Echinodermata and Chordata also lack typical segmentation seen in Annelida.
While many vertebrates have lungs, internal fertilization, and four-chambered hearts, hollow bones with air sacs are unique to birds, enabling them for flight.
During embryonic development, the notochord is replaced by the vertebral column in adult vertebrates, though remnants persist as the nucleus pulposus of intervertebral discs.