How does the seahorse, one of the slowest swimming fish in the sea, manage to capture its nimbler prey? In a word, stealth. Like most fish, seahorses nab their prey by slurping in the water surrounding their victims—a technique called suction feeding. But seahorses can effectively strike at prey only 1 millimeter or so in front of them, so they must approach within that distance (video) without disturbing the water so much that their quarry flees.
New Ichthyological Family Tree Reveals Surprising Cousins
by Becky Oskin
Spiny-rayed fish rule the underwater world.
In the past 100 million years, fish with spiky dorsal and anal fins — an effective anti-predator device — have occupied every nook and cranny of the planet, said Peter Wainwright, an evolutionary biologist at the University of California, Davis.
The group includes more than 90 percent of coral reef fish species and almost everything humans commercially fish, including bass, pollock and tilapia.Now, Wainwright and a team of researchers have pieced together a new family tree for this gigantic brood, with more than 18,000 species living today. Using both genetic tools and fossils, the “phylogeny” reveals unexpected links between some spiny-rayed fish, such as tuna and seahorses. The findings were published July 15 in the journal Proceedings of the National Academy of Sciences.
There are a few species of seahorse that occur off the shores of North America
… the most common and widespread Atlantic species is this, the Lined Seahorse, Hippocampus erectus, found from Nova Scotia all the way to the Gulf of Mexico.
Extremely variable in appearance, the colors, patterns, and spiny projections are all tools used for camouflage. Seahorses are weak swimmers, propelled primarily by the small fin on their back. To catch the brine shrimp and small crustaceans that are their prey, they hide amongst the vegetation and use their tube-like snout to suction food in. Their eyes are like those of chameleons, able to move independently of each other in order to help spot prey. They are actually bony fishes, but lack the scales of typical fish, instead having thin skin stretched over bony plates.
Like their relatives the seahorse, it is the male seadragons which carries its eggs. The females deposits her eggs onto the spongy brood patch of the male, where they are held in place until the hatch.
There are 47 different species of seahorses and 14 of those were discovered in the last eight years, including Pontoh’s pygmy seahorse (Hippocampus pontohi), which was officially named in 2008. Seahorses’ ability to change their color and shape to blend in with their environment makes identification of individual species challenging.
Because of this, some researchers previously thought there were as many as 200 seahorse species in the world, while others thought there were as few as 20. However, advances in genetic research are helping to clarify some of the differences between closely related species.
(CREDIT: Patrick Decaluwe / Guylian Seahorses of the World 2010, Courtesy of Project Seahorse)
Seahorses range in size—from as small as a pine nut to as large as a banana. The largest seahorse species is Hippocampus abdominalis, or the big-bellied seahorse, which can reach more than a foot long (35 cm) and lives in the waters off Southern Australia and New Zealand.
The smallest seahorse, Satomi’s pygmy seahorse (Hippocampus satomiae), which was only described in 2008, is only half an inch long (13 mm)! It lives in the waters of Brunei, Indonesia and Malaysia.
(CREDIT: David Maynard / Guylian Seahorses of the World 2005, Courtesy of Project Seahorse)
Scientists have studied only a handful of species of seahorses (genus Hippocampus), but all of them appear to practice some form of monogamy. After her eggs are fertilized, a female seahorse passes them to her male partner, who carries them in a pouch until they hatch. The males probably incubate one female’s eggs at a time, and it appears that some species remain bonded throughout the breeding season and perhaps even longer.
(photo: Michael Bentley, via: The National Aquarium)
October 11, 2012—The rare West African seahorse has been filmed in the wild for possibly the first time. Researchers hope to learn more about the species and help create a more sustainable trade in the animal. It’s estimated that around 150 million seahorses are sold annually for traditional medicine worldwide.
This 2cm seahorse has evolved to perfectly camouflage against the gorgonian corals which they live on. Its bumps and colouration are so effective that the species was not actually discovered until its host coral was being examined in a laboratory.
The Pygmy Pipehorse, Acentronura tentaculata, showing the cryptic colouration and overall appearance including the projections from the sides of the body. Adults may be found in or just above sandy or muddy substrates, around the base of macro algae, especially red algae, or seagrass and close to or within coral reefs or rocky outcrops… (read more: Wikipedia)