What are some advantages and disadvantages of being big?

Larger animals have better defenses and are more intimidating (many are skilled predators). Being big makes the animal harder to hide, and harder to sustain.

The ratio of an animal's surface area to its total volume(mass) is high for small animals, but low for large animals such as elephants or whales.

This ratio helps large mammals to retain heat which is why in many cold climates there are many larger mammals. In warmer climates mammals have ways to lose this excess heat (elephant ears have high surface area).

Smaller animals lose heat at a much higher rate so to compensate they have very high metabolic rates, this is why smaller animals usually have a short life-span

(less time to grow).

Larger animals live longer (more time to grow) and reproduce at a slower rate so they are more vulnerable to extinction and are less likely to adapt quickly to changing ecosystems.