Double layered nuclear, the outer nuclear membrane is continuous with the membrane of the rough endoplasmic reticulum (ER), it also continues with the inner nuclear membranes since the two layers are fused together at a numerous tiny holes called nuclear pores that perforate the nuclear enevelope
They would most likely die. They could also mate with other animals, thus creating a crossbreed
The study of how living things are classified is called dichotomous key
Ruminant herbivores gain from the microflora in their gut through digestion of cellulose and in return, the microflora gets the nutrients from the ruminants. The shark doesn't benefit from the remora but the remora gets a free ride from the shark and it feeds on the leftovers from the shark's meal. The human host loses nutrients because the tapeworm gets to eat the food provided by the host. Cats provide shelter and food for the flea but the cat becomes anemic because of blood loss from its parasites.