The Intricate Seahorse

The Intricate Seahorse

A cute little thing that one could stare at for hours. Let's take a look at these petite animals' anatomy to get a better understanding of how and why they are the way they are.

The seahorse's scientific genus name, Hippocampus, is Greek for 'bent horse'. Have you noticed how the seahorse may appear as if it wears armour; its body is covered with bony rings and ridges? Its head is shaped like a horse with eyes on the side of the head. 

Anatomy

Seahorses can grow between 10mm to 35cm depending on the species. The smallest seahorse is Satomi's Pygmy seahorse which grows to 11.5mm in height. The largest seahorse is the Big-belly Seahorse, also known as a pot-bellied seahorse, growing to a maximum length of 35cm. 

These creatures are experts at hiding themselves amidst the coral reefs where they live. Some species can actually change the colour of their bodies to blend in, while others are already built with the right colour, shape, size, and texture to blend in perfectly with the corals.

Pygmy seahorse

Pygmy seahorse camouflaged in a sea fan

An interesting fact about their eyes is that they can move independently, looking out for predators and searching for food at the same time. What and how do they eat? Seahorses have no stomachs or teeth... The snout of the seahorse is used to suck in small fish and shellfish. 

Are you wondering how the seahorse manoeuvres underwater? Fins! A seahorse has three main fins: Two pectoral fins behind its gills and One dorsal fin. These fins are used to propel and steer. They are not great swimmers and use their swim bladders to move up and down. They have to beat their fins 50-70 times a second to swim.

Seahorses can make sounds which are similar to the sound of smacking lips. They make these sounds while feeding and during courtship.

Do they really mate for life?

Most species of seahorses studied in the wild do appear to be monogamous, remaining faithful to one partner for the duration of the breeding season and perhaps even over several seasons. Seahorse couples engage in ritualistic dances to greet each other, moving through intricate, rhythmic sequences of twists and twirls for minutes to hours on end. 

We all know that males carry babies. The female deposits her eggs in the male’s pouch, after which the male fertilizes them. The pouch acts like a womb, providing nutrients and oxygen to the developing animals while removing wastes. Another cool thing about this is that the pouch acts like an osmotic adaptation chamber. The internal fluid changes slowly throughout the pregnancy from similar to body fluids to more like the surrounding seawater. This helps reduce the stress on the offspring at birth. As little as five to as many as 1,000 juvenile seahorses, often called ‘fry’ in the fish world, can be born to the world in a single birthing.

Pregnant seahorse

Pregnant seahorse male

Known lifespans for seahorse species range from about one year for the smallest species to an average of three to five years for the larger species. 

What threatens the seahorse?

Seahorses are exploited for use as traditional medicines, aquarium fish, curios (souvenirs), and tonic foods.
Habitat degradation is a real threat to seahorse populations as they mainly inhabit shallow, coastal areas (coral reefs, mangroves, seagrass meadows, estuarine habitats) through human activities. Furthermore, many seahorses are caught accidentally (as bycatch) in fishing nets, particularly in trawl nets intended to catch shrimps.

In the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, 11 of the 35 seahorse species that have been assessed so far are listed as Vulnerable, with one listed as Endangered, one as Near Threatened and two as Least Concern.

If you find these tiny creatures mesmerizing, you can also learn more about weird and wonderful sea slugs.

 

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For the salty at heart

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