A small pore or opening in a sponge's body wall through which water enters the sponge. These numerous tiny openings are the beginning of the sponge's water circulation system.
From Latin 'ostium' meaning door or entrance, from 'os' meaning mouth. The term emphasizes the function of these openings as entry points for water into the sponge's body, like tiny doors in the sponge's surface.
A single sponge can have millions of ostia - they're so small you need a microscope to see them individually, but together they can filter thousands of liters of water per day! It's like having your entire skin covered in microscopic mouths.
Complete word intelligence in one call. Free tier — 50 lookups/day.