List several ways in which obelia differs from hydra

Hydra and Obelia are cnidarians (species of aquatic organisms) that belongs to the Class Hydrozoa.  

Several ways in which Obelia differs from Hydra are;

Hydra is a predative species that lives on substrates such as wood, while Obelia is a colonial species that lives as polyps on  branched frameworks.  Hydra is found in freshwater habitats, while Obelia is found in marine habitats. Hydra undergoes the medusa form in its life cycle, while Obelia undergoes the two forms (polyp and medusa) in its life cycle. Hydra has great regenerative powers while Obelia does not have great regenerative powers.

Explanation:

Many nature groups are conserving areas and habitat where polar bears live and breed. Particularly at Arctic Regions. They also monitors the abundance of prey in a particular polar bear area to ensure its food source. Also governments are making laws and bills mitigating illegal trade of polar bear fur, meat and etc.