How do bacteria and sea sponge reproduce?

They do. They reproduce in three ways:

Sexual Reproduction: Sponges are sessile, which means that they cannot move. Instead of making physical contact, one sea sponge will act as a male and release its sperm into the water. Then another sponge (female) either a meter away or a mile away will absorb the sperm and use it to fertilize itself. The baby sponge will become a free swimming larva, the only time it can swim/move. It will find a plankton rich area to settle down in and grow as a sponge there.

Asexual Reproduction: This is the easier way. A sponge loses a chunk of itself and it grows into a new sponge. This new sponge skips the larva stage and is a 'young sponge' at birth.

Internal Fertilization: A sponge create both the egg and the sperm, thus fertilizing itself.

Note: Some sponges can chose if they want to be male or female, and others can't. Also, some sponges are both male and female.

A video I have found helpful in my research, can be found in the related link