Sea Horses | Marine Biology

These miniature horses are extremely complex creatures that have a very interesting autonomy. While seahorses appear to be very different from other fishes in the sea, they are fish nonetheless. Let’s dive a little deeper into the wonderful world of seahorses.

They are unique in appearance, with their horse-like head, prehensile tail, independently moving eyes, and brood pouch. They have long, tubular snouts and small, toothless mouths. Their bodies are covered with consecutive rings of bony plates. The name of the genus that contains sea horses is taken from the Greek words hippos (meaning “horse”) and kampos (meaning “sea monster”).

Sea horses are rather immobile, swimming more slowly than other fishes. When swimming they maintain a vertical position and propel themselves forward using a soft-rayed dorsal fin. They use pectoral fins located on the side of the head to maneuver. Some scientists contend that this upright swimming posture evolved shortly after the expansion of sea grasses in the western Pacific roughly 25 million years ago. These plants provided sea horses with useful hiding places to avoid enemies and to capture unsuspecting prey, and ancestors of the sea horse evolved to maximize the opportunities offered by this new habitat.

Sea horses are usually found clinging to plants or corals with their tails. Their sedentary habits coupled with excellent camouflage abilities render them successful ambush predators. When we look at a seahorse, we see a creature that barely seems to move -- it seems to more drift, or float with the current. But that very slow movement allows it to sneak up on prey undetected, since it barely disturbs the water around it. Then with a lightning-fast movement of its head, the prey is in the seahorse's mouth before anyone but the seahorse realizes what just happened. Because seahorses move so slowly, they are able to sneak up on them virtually undetected. Once the seahorse is extremely close to the prey, it is able to jerk its head extremely quickly and consume the tiny copepod.

Seahorse males do something highly unusual in the animal kingdom; they get pregnant and deliver their offspring. Scientists don't have a clear reason why seahorses evolved this way, but they theorize this is one of the ways seahorses try to help the species survive. Neither parent gets involved in the child-rearing, though. When the male delivers the babies, they are on their own. Although the male carries the eggs, he doesn't make them. After a male and female seahorse spend time courting, the female deposits her eggs inside the male's pouch. He fertilizes the eggs inside the pouch. His pouch is a complex organ that regulates temperature, blood flow and water salinity for the eggs as they hatch so the babies are as prepared as possible for life in the ocean.

Creating new life takes a lot of energy, which factors into another theory as to why male seahorses carry the babies. When the females create the eggs, she uses her energy to fill the egg casings with nutrients to help the babies mature. This takes some of the stress off the dad. He provides a safe and environmentally controlled environment for his babies, but the mom gives them some food.

Depending on the species, seahorses can deliver from five to more than 1,000 babies at a time. Unfortunately, only about five out of every thousand survive to adulthood. The babies are so tiny that they can't eat the same plankton food as their parents, so their choices are limited.

Population data for most of the world’s more than 30 seahorse species is sparse. However, worldwide coastal habitat depletion, pollution, and rampant harvesting, mainly for use in Asian traditional medicine, have made several species vulnerable to extinction. Seahorses are used in legal and illegal trade for ornamental display, bycatch in the shrimp trawl and other fisheries, and seahorses are extremely threatened by habitat degradation and destruction due to coastal development, marine pollution, coral reef destruction, and land-based deforestation. Deforestation leads to increased siltation in surrounding marine waters, thereby suffocating sea grass bed and killing coral reefs.

If you enjoyed reading this, you might like my previous post on Dolphins, check it out:

https://musings-of-a-musical-biologist.blogspot.com/2021/06/whales-marine-biology.html

 

Citations:

What are Seahorses-

https://www.britannica.com/animal/sea-horse

Are Seahorses good hunters?

https://www.treehugger.com/nature-blows-my-mind-seahorses-are-one-deadliest-creatures-sea-yes-seahorses-4858626

Seahorse reproduction-

https://animals.mom.com/male-seahorses-give-birth-4198.html

Threats to Seahorses-

https://www.nationalgeographic.com/animals/fish/facts/seahorses

https://www.endangeredspeciesinternational.org/seahorse.html