# Zoology (animal science) explained

Beyond cellular life, animals have a more complex existence than plants. They tend to breathe oxygen (O2), then add carbon from their metabolism and emit carbon dioxide (CO2).

A unique quality of fauna is a central control system via a brain. That brain runs on hormone signals that run small bits of electricity through *many* neuron pathways. Each neuron has a big block called a soma (gray matter), with an extension called an axon that's coated in a protective myelin (white matter). The neurons connect via continued exposure to build an automated system of [habits](https://adequate.life/habits/) for responding and interacting with the world.

Except for bugs and some underwater creatures, animals have their skeletons on the inside, with muscles operating them.

As a whole, a brain consists of several inter-related parts:

- A brain stem connected to the spinal cord that manages *very* basic motor skills and sensations.
- A cerebrum that makes up most of the volume of the brain that controls most activities:
  - The frontal lobe is the largest, and regulates [personality](personality.md), [decisions](people-decisions.md), and [movement](reality.md).
  - The parietal lobe helps [identify objects and make relationships](symbols.md) between things.
  - The occipital lobe is at the back, and regulates vision.
  - The temporal lobe is on both sides of the brain at the bottom, and regulates how we perceive time and make stories, which translates to [short-term memory](mind-memory.md), [speech](language.md), musical rhythm, and some aspects of smell.
- A cerebellum that manages higher thought such as [reasoning](understanding.md) and [imagination](imagination.md).
- The brain is split into two hemispheres, with the left side generally managing more [logic](logic.md) and the right side more [emotions](mind-feelings.md). Each hemisphere controls the opposite side of the body.
- Within this framework, there are many deeper structures inside the brain that perform *very* specific things:
  - The pituitary gland is a pea-sized chunk right behind the bridge of the nose and regulates the function of other glands in the body.
  - The hypothalamus is right above the pituitary gland and sends chemical messages to regulate body temperature, synchronize [sleep patterns](sleep.md), control [hunger and thirst](body-2_diet.md), and influence parts of [memory](mind-memory.md) and [emotion](mind-feelings.md).
  - The pineal gland is *very* deep in the brain and manages sleep cycles with the hormone melatonin.
- Also, the limbic system is heavily connected to the brain stem, but extends outward into the cerebrum:
  - The amygdala is an almond-shaped chunk right under each hemisphere of the brain that's part of the limbic system.
  - The hippocampus is on the underside of each temporal lobe that supports [memory](mind-memory.md), [learning](education.md), navigation, and perceiving space.
- The brain emits various types of waves:
  - Delta waves are when a body is in a state of deep [sleep](sleep.md).
  - Alpha waves express when the body is in a state of rest.
  - Beta waves express when the body is alert and engaged.
  - Theta waves are present when someone is daydreaming or in a [flow of ideas](mind-creativity-how.md), and often help remember things connected to space.

Animals require food, which can come from several sources:

- Herbivores eat plants, often existing as prey to other animals.
- Carnivores eat other animals, often as predators.
- Omnivores eat both plants and animals, and may be predators or prey depending on the situation.
- One newly discovered microorganism is a virovore, which eats viruses.

One unique trait of animals is the means of communication via vocal cords. The concept is relatively simple: constrain the flow of air in such a way that sound is produced. This implementation varies wildly across animals, but the abstraction stays the same. Humans, among others, have a unique addition to that with tongues that give *very* precise control over those sounds, and that's how we orchestrate [language](language.md).

Further reading:

- [How does the human eye work?](https://idyll.pub/post/the-eye-5b169094cce3bece5d95e964/)
- [How does color work?](http://jamie-wong.com/post/color/)

Obvious questions that remain unanswered:

- Why do we need sleep?
- Why do we dream?
- Why do we yawn?
- Why do we have fingerprints?
- Why do giraffes have long necks?
- Why do cats purr?
- Approximately how many species of animals exist?

## Ornithology (bird science) explained

Birds are typically defined by egg-laying, moderate nurture of their young, and feathers directly inserted into the skin.

A bird's feathers are typically hollow, which gives the lightweight composition necessary to fly.

Obvious questions that remain unanswered:

- How do birds migrate to the same area every year?

## Entomology (bug science) explained

By far, bugs represent the largest zoological population: most multicellular life on this planet are bugs.

Most of them have a common anatomy:

- Bugs have exoskeletons, with their muscles underneath.
- Antennae/feelers that detect the world around them.
- A head section that represents the same as in mammals.
- Typically, a thorax segment with most of the internal organs.
- An abdomen segment that either contains a specific-purpose organ (e.g., venom sac) or most internal organs (if it doesn't have a thorax).
- Typically, 3 pairs of symmetrical segmented legs, but that number can sometimes be 4 (e.g., spiders) or more (e.g., centipedes, millipedes).
- Depending on the species, wings that empower it to fly. Often, there will be a wing pad on top of it to protect the wings from damage.

Flying bugs navigate around light sources at night because of a navigational error. When the sun is out, they can orient themselves to the light and fly straight, but they're always angled to fly relative to the light source at night as well, meaning they'll keep autocorrecting and be caught in a loop.

Obvious questions that remain unanswered:

- How do monarch butterflies know how to migrate?