Question

1. How does the pace of development vary between the different species? For instance, how does it vary between a zebrafish, a human, a mice, a chicken, and a frog?

Answer 1

Pace of development is different with different species.

In zebrafish, its very fast. The embryonic stage is very fast. The zebrafish after fertilization, it only takes 24 hours to form all the major organs. And it hatches within three days. It becomes sexually mature after 3 to 4 months.

For mice, the gestation period is 19 to 21 days.  The mice are born blind and without fur or ears. The ears are fully developed by the fourth day. The fur begins to appear at about six days. The eyes open around 13 days after birth. Female mice  reach sexual maturity at about six weeks of age and male mice reach it at about eight weeks.

Frogs lay eggs and inside the egg, the division takes place. After 6-21 days after fertilization, the egg hatches. It is now a tadpole and it start to grow after 6 weeks and complete growing after 9 weeks. By 12 weeks, it becomes a frog with tail. Within 16 weeks, it becomes a frog.

For chicken, it takes 21 days to hatch. They reach sexual maturity after 16 to 24 weeks.

For humans, the gestation period is 40 weeks. The fetus grows from 4 th month to 9 th month of pregnancy. By birth, the humsns are almost developed. After birth , the speed of growth is slow. But in adolescent period growth spurt happens. The males become sexually mature between ages 12 and 16 and the females become sexually mature between ages 10 and 14.