Spawning Sea Cucumbers! They look dirty but they're really not!

So, following up my account of asteroid spawning underscoring behavior that is often seen but not really well-studied, here's something similar from the tropical sea cucumber oeuvre!

How does the posture help? Does it assist in optimal fertilization? Why don't all species assume the posture?

Its worth noting that even though a lot of the YouTube descriptions say they are "males releasing sperm" the truth is that there's no way to sex sea cucumbers from external appearance (that I know of).

So, what you're seeing below is either eggs OR sperm. I.e., gametes or reproductive cells are being produced...by either males OR females..

hmm..this one might be interpreted badly if you have a smutty mind..