Overproduction
Most species produce more offspring than can survive.
Competition
Since living space and food are limited, organisms must compete for the necessities.
Variation
Differences between individuals in a population.
Adaptations
Any kind of inherited trait that improves an organism's chances of survival.
Natural selection
The environment selects organisms with optimal traits to be the parents of the next generation.
Speciation
Over many generations, favorable adaptations accumulate and may result in a new species.
Some causes could be the mother smoking, drinking, doing drugs etc. Or even simply her body doesn’t fully accept the baby growing inside her so it acts out against it. Sounds strange but it happens. Also if the mother is sick with Zika or another virus, it can harm the baby’s growth.
1. SI,
2. Number 10.
I'm pretty sure it's that, I just did something related to that.
some of the special structures in the members of these phylum as follows:
Members of porifera are sponges. they have collar cells and cellular -level body organization. Cnidarian have stinging cells present on the tentacles around the mouth. Ctenophorans have comb-like plate cells for swimming. Platyhelminthes - members are first to have sensory and nervous tissue in the head region.