1. The young ones resemble the adult directly and no larval stages occur.
2. The eggs of these animals have lot of yolk for the young ones to grow or are fed by the mother's tissues (human being) in the larval stages.
3. Parental care is seen in many cases.
Disadvantages:
1. Since the parents and young ones are found in the same habitat they have to share the same resources.
2. In case of calamities/disasters, they will die together.
