Very early in the evolutionary history of animals, there was a divergance that would ultimately lead to the creation of two major divisions in the Kingdom Animalia; the Protostomes & Deuterostomes. In this episode, we'll explore this ancient evolutionary split, the physiological differences between the two clades, and the modern descendant species that represents them today.

The animal endocrine system is a complex decentralized chemical communication network that coordinates growth and homeostasis across the whole organism. Hormones are a critical component of this system, and we'll explore the many forms they can take. And while we're on the topic of glands, we'll also cover the basics of the exocrine system.

Today we'll examine the chemistry, anatomy, and physiology of the animal nervous system, from action potentials to neural circuits to animal behavior.

In this episode, we'll explore the complex dynamics of the defensive system that protects animals from the countless microbes and pathogens they encounter every day: the immune system!

In this episode, we'll explore both the chemistry and physiology of animal respiration. This will also involve a brief exploration of the cardiovascular system, which is integral to the function of the respiratory system.

The subtle but foundational relationship between form and function can be seen at all levels of biological organization, from cells to tissues to organs to limbs and body plans.

The ability to move, freely & autonomously, is one of the defining characteristics of all but the most basal animals, distinguishing them from the stationary plants, and the creeping fungi.

Animals are some of the most complex and dynamic organisms on Earth, and their mechanisms for reproduction are just as varied and complex.

An animal uses its senses to perceive and engage with the world around it, which is critical when you can move around an environment, searching for prey, and escaping predators.

All animals must eat food to survive, but how an animal eats, how often, and what it eats, play a fundamental role in the animal's evolution.