General Animal Features:
* Eukaryotic cells: Reptiles, like all animals, are made up of cells with a membrane-bound nucleus and other organelles.
* Multicellular: They are composed of multiple cells organized into tissues, organs, and organ systems.
* Heterotrophic: They obtain their nutrients by consuming other organisms (plants or animals).
* Mobility: Reptiles are capable of movement, although some may be more sedentary than others.
* Reproduce sexually: Reptiles typically reproduce sexually, involving the fusion of male and female gametes.
* Growth and development: Reptiles grow and develop from embryos, and often undergo metamorphosis.
Reptile-Specific Features:
* Amniotic egg: A key feature of reptiles, birds, and mammals. The amniotic egg allows them to reproduce on land, as it provides a protective environment for the developing embryo.
* Scales: Reptiles have scales, which are made of keratin (the same protein found in human hair and nails). Scales provide protection and help regulate temperature.
* Cold-blooded (ectothermic): Reptiles rely on external sources of heat to regulate their body temperature. They may bask in the sun to warm up or seek shade to cool down.
* Respiration: Reptiles breathe air using lungs.
* Closed circulatory system: Reptiles have a heart and blood vessels to circulate blood throughout their bodies.
Key takeaway: While reptiles possess specific features that distinguish them from other animal groups, they share the fundamental characteristics of the animal kingdom, making them undeniably animals.