This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
Animals generally don't have organs that are useless.
Every organ is useful either for maintaining temperature....and much more.

All organs are useful in animals body.But there are some certain organs which are once useful and became useless during the course of evolution.For example, consider males,in them mammary glands are useless and in human beings hair on skin,diaphragm etc are useless.But in herbivores,diaphragm is very useful.