Riptide horrors mate once a year, usually in flooded sea caves. The female crawls into the male's lair and deposits a sticky, greenish-tan mass of eggs on the wall of the cave. The male fertilizes the eggs, and in 4 months, the eggs begin to hatch. Juveniles are excellent swimmers and leave the cave as soon as they hatch. As a riptide horror ages, its body secretes a substance that forms a shell-like carapace on its dorsal side.