How do echinoderms reproduce by spawning?

Echinoderms typically reproduce through a process called spawning, in which males and females shed their spermatozoa and eggs directly into the water column for external fertilization.12

Key aspects of this process include:

• Timing and Coordination: Most species spawn on an annual cycle, often during spring or summer, triggered by environmental factors like temperature, light, or salinity. Some species, such as certain feather stars, coordinate spawning with lunar phases.1
• Behavioral Adaptations: To increase the probability of successful fertilization, many echinoderms aggregate before spawning. Some species exhibit specific behaviors, such as raising the center of the body off the seafloor or waving the front end of the body, to prevent gametes from becoming trapped in sediment.1
• Hormonal Regulation: In sea stars, the process is regulated by a neuropeptide known as gonad-stimulating substance, which triggers the production of 1-methyladenine to induce oocyte maturation and spawning.3
• Scale: The process is highly prolific; a single female starfish can release millions of eggs in a single season.2