Learn About Seahorses

In this episode of the I Can't Sleep Podcast, fall asleep learning about seahorses. Sure, they look cool on National Geographic and other nature documentaries. However, contrary to their fascinating appearance, learning about seahorses can be quite mundane. Happy sleeping!

Transcript

Welcome to the I Can't Sleep podcast,

Where I read random articles from across the web to bore you to sleep with my soothing voice.

I'm your host,

Benjamin Boster.

Today's episode is from a Wikipedia article titled,

Seahorse.

A seahorse is any of 46 species of small marine fish in the genus Hippocampus.

Seahorse comes from the ancient Greek Hippocampos,

Itself from Hippos,

Meaning horse,

And Campos,

Meaning sea monster or sea animal.

Having a head and neck suggestive of a horse,

Seahorses also feature segmented bony armor,

An upright posture,

And a curled prehensile tail.

Along with the pipefishes and sea dragons,

They form the family Cygnathidae.

Seahorses are mainly found in shallow tropical and temperate salt water throughout the world,

From about 45 degrees south to 45 degrees north.

They live in sheltered areas such as seagrass beds,

Estuaries,

Coral reefs,

And mangroves.

Four species are found in Pacific waters from North America to South America.

In the Atlantic,

Hippocampus erectus ranges from Nova Scotia to Uruguay.

H.

Zosteri,

Known as the dwarf seahorse,

Is found in the Bahamas.

Colonies have been found in European waters such as the Thames estuary.

Three species live in the Mediterranean Sea,

H.

Cotulatus,

The long-snouted seahorse,

H.

Hippocampus,

The short-snouted seahorse,

And H.

Fuscus,

The sea pony.

These species form territories.

Males stay within 1 m2 of habitat,

While females range over about 100 times that.

Seahorses range in size from 1.

5 to 35 cm.

They are named for their equine appearance,

With bent necks and long-snouted heads and a distinctive trunk and tail.

Although they are bony fish,

They do not have scales,

But rather thin skin stretched over a series of bony plates,

Which are arranged in rings throughout their bodies.

Each species has a distinct number of rings.

The armor of bony plates also protects them against predators,

And because of this outer skeleton they no longer have ribs.

Seahorses swim upright,

Propelling themselves using the dorsal fin,

Another characteristic not shared by their close pipefish relatives,

Which swim horizontally.

Razorfish are the only other fish that swim vertically.

The pectoral fins,

Located on either side of the head behind their eyes,

Are used for steering.

They lack the caudal fin typical of fishes.

Their prehensile tail is composed of square-like rings that can be unlocked only in the most extreme conditions.

They are adept at camouflage and can grow and resorb spiny appendages depending on their habitat.

Usual among fish,

A seahorse has a flexible,

Well-defined neck.

It also sports a crown-like spine or horn on its head,

Termed a coronet,

Which is distinct for each species.

Seahorses swim very poorly,

Rapidly fluttering a dorsal fin and using pectoral fins to steer.

The slowest-moving fish in the world is H.

Sastri,

The dwarf seahorse,

With a top speed of about 1.

5 meters per hour.

Since they are poor swimmers,

They are most likely to be found resting with their prehensile tail wound around a stationary object.

They have long snouts,

Which they use to suck up food,

And their eyes can move independently of each other like those of a chameleon.

Anatomical evidence,

Supported by molecular,

Physical,

And genetic evidence,

Demonstrates that seahorses are highly modified pipefish.

The fossil record of seahorses,

However,

Is very sparse.

The best-known and best-studied fossils are specimens of Hippocampus guttulatus,

Though literature more commonly refers to them under the synonym of H.

Remolosus,

From the Marechia River formation of Rimini province,

Italy,

Dating back to the Lower Pliocene,

About three million years ago.

The earliest known seahorse fossils are of two pipefish-like species,

H.

Sarmaticus and H.

Slovenicus,

From the coprolitic horizon of Tungus Hills,

A middle Miocene laga strata in Slovenia,

Dating back about 13 million years ago.

Molecular dating implies that pipefish and seahorses diverged during the Late Oligocene.

This has led to speculation that seahorses evolved in response to large areas of shallow water,

Newly created as a result of tectonic events.

The shallow water would have allowed the expansion of seagrass habitats that served as camouflage for the seahorse's upright posture.

These tectonic changes occurred in the western Pacific Ocean,

Pointing to an origin there with molecular data suggesting two later separate invasions of the Atlantic Ocean.

In 2016,

A study published in Nature found the seahorse genome to be the most rapidly evolving fish genome studied so far.

The evolution of seahorses from pipefish may have been an adaptation related to the biomechanics of prey capture.

The unique posture of the seahorse allows them to capture small shrimps at larger distances than the pipefish is capable of.

The male seahorse is equipped with a brood pouch on the ventral or front-facing side of the tail.

When mating,

The female seahorse deposits up to 1,

500 eggs in the male's pouch.

The male carries the eggs for 9 to 45 days until the seahorses emerge fully developed,

But very small.

The young are then released into the water,

And the male often mates again within hours or days during the breeding season.

Before breeding,

Seahorses may court for several days.

Scientists believe the courtship behavior synchronizes the animal's movements and reproductive states so that the male can receive the eggs when the female is ready to deposit them.

During this time,

They may change color,

Swim side-by-side holding tails,

Or grip the same strand of seagrass with their tails,

And wheel around in unison in what is known as a pre-dawn dance.

The number of young released by the male seahorse averages 100 to 1,

000 for most species,

But may be as low as 5 for smaller species,

Or as high as 2,

500.

When the fry are ready to be born,

The male expels them with muscular contractions.

He typically gives birth at night and is ready for the next batch of eggs by morning when his mate returns.

Like almost all other fish species,

Seahorses do not nurture their young after birth.

Infants are susceptible to predators or ocean currents which wash them away from feeding grounds or in temperatures too extreme for their delicate bodies.

Less than 0.

5% of infants survive to adulthood,

Explaining why litters are so large.

These survival rates are actually fairly high compared to other fish because of their protected gestation,

Making the process worth the great cost to the father.

The eggs of most other fish are abandoned immediately after fertilization.

Though seahorses are not known to mate for life,

Many species form pair bonds that last through at least the breeding season.

Some species show a higher level of mate fidelity than others,

However many species readily switch mates when the opportunity arises.

Although monogamy within fish is not common,

It does appear to exist for some.

In this case,

The mate-guarding hypothesis may be an explanation.

This hypothesis states,

Males remain with a single female because of ecological factors that make male parental care and protection of offspring especially advantageous.

Because the rates of survival for newborn seahorses are so low,

Incubation is essential.

Though not proven,

Males could have taken on this role because of the lengthy period the females require to produce their eggs.

If males incubate while females prepare the next clutch,

Amounting to a third of body weight,

They can reduce the interval between clutches.

Seahorses use their long snouts to eat their food with ease.

However they are slow to consume their food and have extremely simple digestive systems that lack a stomach,

So they must eat constantly to stay alive.

Seahorses are not very good swimmers,

And for this reason they need to anchor themselves to seaweed,

Coral,

Or anything else that will keep the seahorse in place.

They do this by using their prehensile tails to grasp their object of choice.

Seahorses feed on small crustaceans floating in the water or crawling on the bottom.

With excellent camouflage,

Seahorses ambush prey that floats within striking range,

Sitting and waiting until an optimal moment.

Mizzid shrimp and other small crustaceans are favorites,

But some seahorses have been observed eating other kinds of invertebrates and even larval fish.

In a study of seahorses,

The distinctive head morphology was found to give them a hydrodynamic advantage that creates minimal interference while approaching an evasive prey.

Thus the seahorse can get very close to the copepods on which it preys.

After successfully closing in on the prey without alerting it,

The seahorse gives an upward thrust and rapidly rotates the head,

Aided by large tendons that store and release elastic energy,

To bring its long snout close to the prey.

This step is crucial for prey capture,

As oral suction only works at a close range.

This two-phase prey capture mechanism is termed pivot feeding.

Seahorses have three distinctive feeding phases,

Preparatory,

Expansive,

And recovery.

During the preparatory phase,

The seahorse slowly approaches the prey while in an upright position,

After which it slowly flexes its head ventrally.

In the expansive phase,

The seahorse captures its prey by simultaneously elevating its head,

Expanding the buccal cavity,

And sucking in the prey item.

In the recovery phase,

The jaws,

Head,

And hyoid apparatus of the seahorse return to their original positions.

The amount of available cover influences the seahorse's feeding behavior.

For example,

In wild areas with small amounts of vegetation,

Seahorses will sit and wait,

But an environment with extensive vegetation will prompt the seahorse to inspect its environment,

Feeding while swimming,

Rather than sitting and waiting.

Conversely,

In an aquarium setting with little vegetation,

The seahorse will fully inspect its environment and makes no attempt to sit and wait.

Because data is lacking on the sizes of the various seahorse populations,

As well as other issues including how many seahorses are dying each year,

How many are being born,

And the number used for souvenirs,

There is insufficient information to assess their risk of extinction,

And the risk of losing more seahorses remains a concern.

Some species,

Such as the paradoxical seahorse H.

Paradoxus,

May already be extinct.

Coral reefs and seagrass beds are deteriorating,

Producing viable habitats for seahorses.

Additionally,

Bycatch in many areas causes high cumulative effects on seahorses,

With an estimated 37 million individuals being removed annually over 21 countries.

While many aquarium hobbyists keep them as pets,

Seahorses collected from the wild tend to fare poorly in home aquaria.

Many eat only live foods,

Such as brine shrimp,

And are prone to stress,

Which damages their immune systems and makes them susceptible to disease.

In recent years,

However,

Captive breeding has become more popular.

Such seahorses survive better in captivity and are less likely to carry diseases.

They eat frozen crustaceans that are readily available from aquarium stores and do not experience the stress of moving out of the wild.

Although captive-bred seahorses are more expensive,

They take no toll on wild populations.

Seahorses should be kept in an aquarium with low-flow and placid tankmates.

They are slow feeders,

So fast,

Aggressive feeders will leave them without food.

Seahorses can coexist with many species of shrimp and other bottom-feeding creatures.

Gobies also make good tankmates.

Seahorses are generally advised to avoid eels,

Tangs,

Triggerfish,

Squid,

Octopus,

And sea anemones.

Water quality is very important for the survival of seahorses in an aquarium.

They are a delicate species which should not be added to a new tank.

The water parameters are recommended to be as follows,

Although these fish may acclimatize to different water over time.

Temperature 23-28°C,

PH 8.

1-8.

4,

Ammonia 0mg per liter,

Nitrite 0mg per liter,

Sg 1.

021-1.

024 at 23-24°C.

A water quality problem will affect fish behavior and can be shown by clamped fins,

Reduced feeding,

Erratic swimming,

And gasping at the surface.

Seahorses swim up and down as well as using the length of the aquarium.

Therefore,

The tank should ideally be twice as deep as the length of the adult seahorse.

Animals sold as freshwater seahorses are usually the closely related pipefish,

Of which a few species live in the lower reaches of rivers.

The supposed true freshwater seahorse,

Called H.

Imae,

Is not a valid species,

But a synonym sometimes used for barbers and hedgehog seahorses.

The latter,

Which is often confused with the former,

Can be found in estuarine environments but is not actually a freshwater fish.

Seahorses are consumed by certain populations around the world,

Including Japan,

Where it is relatively popular.

Some seahorse species are consumed by practitioners of traditional medicine,

Including traditional Chinese medicine,

Indonesians,

Central Filipinos,

And many other ethnic groups.

Up to 20 million seahorses may be caught each year to be sold for such uses.

Traded species of seahorses include H.

Kelogi,

H.

Hystrix,

H.

Kuda,

H.

Trimaculatus,

And H.

Moniki.

Import and export of seahorses has been controlled under CITES since 15 May 2004.

However,

Indonesia,

Japan,

Norway,

And South Korea have chosen to opt out of the trade rules set by CITES.

On the basis of the newest overall taxonomic review of the genus Hippocampus with further new species and partial taxonomic review,

The number of recognized species in this genus is considered to be 46,

Retrieved May 2020.

Big-bellied seahorse,

West African seahorse,

Narrow-bellied seahorse,

Barber's seahorse,

Pygmy seahorse,

Short-headed seahorse,

Giraffe seahorse,

Nisna seahorse,

Bay-boo-bay seahorse,

Coleman's pygmy seahorse,

Tiger-tail seahorse,

Crowned seahorse,

Caledonian seahorse,

Low-crowned seahorse,

Soft-coral seahorse,

Denise's pygmy seahorse,

Fisher's seahorse,

Long-snouted seahorse,

Korean seahorse,

Short-snouted seahorse,

Spiny seahorse,

Pacific seahorse,

Japanese pygmy seahorse,

Jaeger seahorse,

Collared seahorse,

Great seahorse,

Spotted seahorse,

Bull-necked seahorse,

Japanese seahorse,

South African pygmy seahorse or Sudwana pygmy seahorse,

Paradoxical seahorse,

Patagonian seahorse,

Flat-faced seahorse,

False-eye seahorse,

Ponto's pygmy seahorse,

Pygmy-thorny seahorse,

Long-snouted seahorse,

Satomi's pygmy seahorse,

Sindho's seahorse,

Hedgehog seahorse,

West Australian seahorse,

Long-nosed seahorse,

Tyro's seahorse,

Wallea's soft coral pygmy seahorse,

White's seahorse,

Zebra seahorse,

Dwarf seahorse.

Pygmy seahorses are those members of the genus that are less than 15 millimeters wide.

Previously,

The term was applied exclusively to the species H.

Argobonti,

But since 1997,

Discoveries have made this usage obsolete.

The species H.

Minotaur,

H.

Denise,

H.

Colomani,

H.

Pontoi,

H.

Cervenci,

H.

Tamanii,

H.

Satomi,

H.

Walianonus,

H.

Nalu,

H.

Japapigu have been described.

Other species that are believed to be unclassified have also been reported in books,

Dive magazines,

And on the internet.

They can be distinguished from other species of seahorse by their 12 trunk rings,

Low number of tail rings,

The location in which young are brooded in the trunk region of males,

And their extremely small size.

Molecular analysis of 32 hippocampus species found that H.

Argobonti belongs in a separate clade from other members of the genus,

And therefore that the species diverged from the other species in the ancient past.

Many pygmy seahorses are well camouflaged and live in close association with other organisms,

Including colonial hydrazoans,

Coraline algae,

And sea fans.

This,

Combined with their small size,

Accounts for why most species have only been noticed and classified since 2001.

Hypefish look like straight-bodied seahorses with tiny mouths.

The name is derived from the peculiar form of the snout,

Which is like a long tube,

Ending in a narrow and small mouth which opens upwards and is toothless.

The body and tail are long,

Thin,

And snake-like.

They each have a highly modified skeleton formed into armored plating.

This dermal skeleton has several longitudinal ridges,

So a vertical section through the body looks angular,

Not round or oval as in the majority of other fishes.

A dorsal fin is always present and is the principle in some species the only.

Organ of locomotion.

The ventral fins are consistently absent and the other fins may or may not be developed.

The gill openings are extremely small and placed near the upper posterior angle of the gill cover.

Many are very weak swimmers in open water,

Moving slowly by means of rapid movements of the dorsal fin.

Some species of pipefish have prehensile tails as in seahorses.

A majority of pipefishes have some form of a caudal fin,

Unlike seahorses,

Which can be used for locomotion.

Some species of pipefish have more developed caudal fins,

Such as the group collectively known as flag-tailed pipefish,

Which are quite strong swimmers.

Most pipefishes are marine dwellers.

Only a few are freshwater species.

They are abundant on coasts of the tropical and temperate zones.

Most species of pipefish are usually 35 to 40 centimeters in length and generally inhabit sheltered areas in coral reefs or seagrass beds.

Due to their lack of strong swimming ability,

Pipefish are often found in shallow waters that are easily disturbed by industrial runoffs and human recreation.

Shorelines are also affected by boats and drag lines that move shoreline sediment.

These disturbances cause a decrease in seagrasses and eelgrasses that are vital in pipefish habitat.

The pipefish's narrow range distribution indicates that they are less able to adapt to new habitats or habitat change.

Another factor that affects pipefish population is their use in traditional Chinese medicine,

TCM remedies,

Despite the lack of evidence of efficacy beyond placebo.

Cygnacity in general are in high demand for pseudoscientific medicinal cures,

But pipefish are even more exploited because of a belief in their higher level of potency,

Because they are longer than the more common variety of seahorses.

The aquarium trade of pipefish has also increased in recent years.

Pipefishes,

Like their seahorse relatives,

Leave most of the parenting duties to the male,

Which provides all of the post-zygotic care for its offspring,

Supplying them with nutrients and oxygen through a placenta-like connection.

It broods the offspring either on distinct region of its body or in a brood pouch.

Brood pouches vary significantly among different species of pipefish,

But all contain a small opening through which female eggs can be deposited.

The location of the brood pouch can be along the entire underside of the pipefish or just at the base of the tail,

As with seahorses.

Pipefish in the genus Cyngnathus have a brood pouch with a ventral seam that can completely cover all of their eggs when sealed.

In males without these pouches,

Eggs adhere to a strip of soft skin on the ventral surface of their bodies that does not contain any exterior covering.

The evolution of male brooding in pipefish is thought to be a result of the reproductive advantage granted to pipefish ancestors that learn to deposit their eggs onto the males,

Who could escape predation and protect them.

Furthermore,

The ability to transfer immune information from both the mother in the egg and the father in the pouch,

Unlike other chordates in which only the mother can transfer immune information,

Is believed to have an additive beneficial effect on offspring immunity.

The dorsal fin is a fin located on the back of most marine and freshwater vertebrates.

In various taxa of the animal kingdom,

Many species of animals possessing dorsal fins are not particularly closely related to each other,

Though through convergent evolution,

They have independently evolved external superficial fish-like body plans adapted to their marine environments,

Including most numerously fish,

But also mammals such as cetaceans,

Whales,

Dolphins,

And porpoises,

And even extinct ancient marine reptiles such as various known species of ichthyosaurs.

Most species have only one dorsal fin,

But some have two or three.

Wildlife biologists often use the distinctive nicks and wear patterns which develop on the dorsal fins of large cetaceans to identify individuals in the field.

The bony or cartilaginous bones that support the base of the dorsal fin in fish are called tergiophores.

The main purpose of the dorsal fin is to stabilize the animal against rolling and to assist in sudden turns.

Some species have further adapted their dorsal fins to other uses.

The sunfish uses the dorsal fin for propulsion.

In anglerfish,

The anterior of the dorsal fin is modified into a biological equivalent to a fishing pole and a lure,

Known as illicium or esca.

Many catfish can lock the leading ray of the dorsal fin in an extended position to discourage predation or to wedge themselves into a crevice.

Some animals have developed dorsal fins with protective functions such as spines or venom.

For example,

Both the spiny dogfish and the Port Jackson shark have spines in their dorsal fins which are capable of secreting venom.

Billfish have prominent dorsal fins.

Like tuna,

Mackerel,

And other scombroids,

Billfish streamline themselves by retracting their dorsal fins into a groove in their body when they swim.

The shape,

Size,

Position,

And color of the dorsal fin varies with the type of billfish and can be a simple way to identify a billfish species.

For example,

The white marlin has a dorsal fin with a curved front edge and is covered with black spots.

The huge dorsal fin or sail of the sailfish is kept retracted most of the time.

Sailfish raise them if they want to herd a school of small fish and also after periods of high activity,

Presumably to cool down.

A dorsal fin is classified as a medial,

Unpaired fin that is located on the midline of the backs of some aquatic vertebrates.

In the development of the embryo in teleost fish,

The dorsal fin arises from sections of the skin that form a caudal fin fold.

The larval development and formation of the skeleton that support the median fins in adults result in tear joints The skeletal elements of the tear geophore includes basals and radials.

The basals are located at the base of the dorsal fin and are closest to the body.

The radials extend outward from the body to support the rest of the fin.

These elements serve as attachment sides for apaxial muscles.

The muscles contract and pull against the basals of the tear geophores along the side of the body,

Which helps the fish move through water by providing greater stability.

In these types of fish,

The fins are made of two main components.

The first component is the dermal fin rays known as lepidotrichia and the endoskeletal base with associated muscles for movement is the second.

Reviews

I remember commercials about seahorses (yes, I’m THAT old 😂😂😂). Not sure if you talked about that because I went right to sleep. 😊😊