How do Seahorses Reproduce?

Hippocampus hippocampus, Credit:Wikimedia/Hans Hillewaert,

Seahorses are beautiful, no doubt about it. Anyone who has been diving and seen a seahorse in its natural environment will agree. Seahorses can change color, move their eyes independently of one another, and even possess prehensile tails (like monkeys).


The fact that both male and female seahorses can get pregnant and have babies will leave you in awe of these amazing fish. Male seahorses and their close relatives, pipefishes and sea dragons, are the only male animals in the whole animal kingdom that get pregnant and have babies.


A female moves eggs into the closed brood pouch of a male. The male then fertilizes the eggs, so he knows for sure who the father is, which is unusual for an animal.


The embryos settle into the tissue of the brood pouch, where a network of capillaries gives them oxygen and a placental fluid gives them food (with adult diet apparently affecting embryonic development).


Depending on the species and water temperature, a male’s pregnancy lasts between 10 days and 6 weeks. During this time, the pouch environment changes to become more like the ocean.


At the end of the pregnancy, the male goes into labor and pumps and pushes for hours to get the babies out of the pouch. Depending on the species, he may release anywhere from a few to several thousand embryos. Most species’ young are 8 to 10 mm long.


From that point on, the young are completely on their own. Most of them drift around as plankton, and the male is ready to mate again.


In many species, but not all, a male and a female stay together for a long time. The pair bond is so strong that the female will keep coming back to the male even if she gets hurt and can’t mate or have babies. It also seems to be helpful, since seahorses that can mate quickly mate again, and those that stay together for a long time tend to have more babies.


Prehensile tail: The tail of an animal with modified grasping or holding abilities


Brood pouch: A pouch that protects the eggs before hatching which is found in several fish, frogs, and invertebrates.


Capillaries: Delicate blood vessels that are found throughout the body that provide blood, nutrients, and oxygen to cells.


Placental fluid: Fluid that cushions the developing fetus and also helps the mother and fetus exchange nutrients and water


Plankton: Floating organisms that drift on currents and tides in saltwater or freshwater. Plankton includes microscopic plants and animals, and mostly species less than one inch in length, but it also includes larger species, like crustaceans.

Flesch Kincaid Grade Level: 68.3


Flesch Kincaid Reading Ease: 8.2

Copyright @smorescience. All rights reserved. Do not copy, cite, publish, or distribute this content without permission.

Join 20,000+ parents and educators
To get the FREE science digest in your inbox!