"digestive"
The circulatory system
The excretory system.
The reproductive system...
nervous system
Because sponges have seawater to carry nutrients and waste.
There are two different organs which are part of the digestive system and which are responsible for breaking down some types of nutrients, these being the stomach and the small intestine. The digestive system also includes other organs but those do not break down nutrients.
The circulatory system is responsible for absorbing nutrients from the digestive system. In addition, it works to carry these nutrients throughout the body.
absorption
so that the nutrients are absorbed to the blood stream
When nutrients are digested they are then absorbed into the blood stream. The cardiovascular system then distributes those nutrients to the different areas of the body that are in need of them.
The stomach, small intestine, and large intestine are the digestive organs responsible for absorbing nutrients.
digestive system
The small intestine is responsible for the absorption of nutrients.
http://wiki.answers.com/FAQ/6462excretory
circulatory system
The blood system
The digestive system has primary responsibility for breaking down food.