Post by Amanda “not a sponge” Kahn. Amanda Kahn is currently a masters student at well-known Moss Landing Marine Laboratory, considered to be one of the west coast’s premier marine stations. Despite still being in her masters, she is quickly becoming the “go-to” person for deep-sea sponges.
Let’s start off “sex week” with the steamy sex life that fuels reproduction within Phylum Porifera, the sponges. Part of the intrigue of sponge reproduction is that it is still mysterious—very few studies have been done. Many sponges are hermaphroditic, others never change sexes in their whole life. Still others alternate once or many times between being male and female.
Most research on sponge reproduction has been done on shallow-water sponges, with only inferences drawn for deep-sea sponges. Unlike every other animal, sponges don’t have organized gonads. Instead, sperm are produced in and float around in the sponge’s innards (called the mesohyl). Sperm billow from excurrent canals like smoke coming from chimneys, coating the nearby surroundings in sponge unmentionables. “Smoking sponges” can be triggered one at a time or in whole sleezes* of sponges (see video below). Sperm release may happen many times throughout the year or in one massive discharge one night when the moon is right. When sperm is pumped inside the feeding chambers of another sponge, if you know what I mean, the feeding cells in the chamber transform into sperm transport cells. The sperm is packaged up and is brought to fertilize an oocyte. After fertilization, sponge larvae are released into the water and either drift to a new location, or for glass sponges, drift or crawl to a new place to grow up.
Just in case sex isn’t enough, sponges can reproduce asexually as well. Stick a sponge in a blender and you’ll end up with thousands. Some sponges bud new offspring, while others produce cyst-like structures that withstand harsh conditions. The saucy exploits of sponge sex have already introduced you to sleezy topics and smoking sponges—and this is just the beginning of sex week!
*Like a crash of rhinos or a gaggle of geese, an aggregation of sponges has its own collective name: a sleeze. About one person in the world knows of this term: the student who coined it in 1978. The term hasn’t caught on yet, but only because the details of sponge sex are not yet common knowledge.