Compare respiratory systems of earthworm, frog and squid. explain how the specimen breathes and which organ are involved.

Earthworm: Gas exchange through skin  

Snake: epiglottis, trachea, and nostrils  

Frog: gills, skin or underdeveloped lungs

Squid:  through the mantle

Explanation:

Earthworm uses its skin to gas exchange.

Snakes have external nares, nasal cavity, internal nares, glottis, trachea, bronchi, lung(s) and air sac. they breath  

All frogs go through a process called metamorphosis, where they use gills however mature frogs lose gills and bring oxygen into their bodies through underdeveloped, lungs. Skin also helps them to use oxygen from water.

The squid has gills in their mantle. Water enters into the mantle from the mantle opening. Gas exchange takes place through the water.