Animal Diversity

1. What two challenges faced by organisms living on

land? How have insects and tetrapods

dealt with these challenges?

- Challenge 1- breathing o2- the partial pressure of o2 is much higher on land than in water and and land animals have a much greater oxygen need than animals in water. Tetra pods have adapted to this challenge by developing lungs that are supplied by blood for gas exchange. The blood is then circulated throughout the body by blood vessels, providing oxygen. Insects do not have lungs or blood vessels that circulate o2. Instead, they have adapted to the challenge of breathing on land by developing a tracheal system. This system relies on a network of small tubes (tracheae) that connect directly to the air through openings in the body wall (spiracles. The tracheae branch into smaller tubes (tracheoles) that connect to the plasma membrane of each cell in the insects body. The plasma membrane is where o2 and co2 are exchanged.

- Challenge 2- support on land. Water dwelling animals are supported by the water they live in so they exert much less effort holding themselves up compared to land animals. Tetrapods have adapted to this by developing strong bones and vertebrae on their legs that are integrated with muscles for support and movement. Insects of the of the subphylum Hexapoda have indirect or direct muscles or both (orthoptera and odonata) for support and movement of their wings for flight.

2. Explain why the insect tracheal system would not be

efficient for tetrapods. How does the

tracheal system influence the structure and function of other organ systems?

The fact that tetrapods have a closed circulatory system makes the insect tracheal system inefficient for them. Insects have an open circulatory system and the o2 from the air goes directly to every cell in their body which would be very complicated in tetrapods.

The tracheal system influences structure and function of other organs because it grows disproportionately larger than the organs, forcing them to be much smaller in order for there to be room for everything to fit in the insects body.