Yes they are.
tube sponges come in many natural colors such as brown, dull green and yes, yellow. secondly tube sponges reproduce by spliting their selves in half. so i guess their only family is the one sponge.
zooplankton
porifera
not necessarily .
a type of sponge that is purple
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They are shaped like a tube!
They eat bacteria, plankton and detritus.
Many coral reef organisms eat yellow tube sponges like angelfishes, filefishes, cowfishes and spadefish. Also the Hawksbill sea turtle.
i dont think i know ... :P
Some enemies are algae and barnacles.
There are many different kinds of sponges. Every time you see a sponge with a different shape and color, that is a different species. There are thousands of different species of sponges, tube sponges, encrusting sponges, demosponges, etc. But yes, Porifera only includes sponges. So sponges are the only animals in the Porifera.