Tiny Seahorses Growl When Perturbed
Source: Smithsonian National Zoo, Jochen Lü
Tamarins and Marmosets
June 14, 2011 --
No matter the species, human or otherwise, it's tough being a parent. In honor of Fathers' Day, take a moment to get acquainted with some of the animal world's best dads. With a baby face like that, it's probably not hard for a father tamarin to love his offspring. Marmosets and tamarins, small monkeys in the subfamily Callitrichinae are native to the Amazon rainforests and are known for being good helpers for mothers. Females generally give birth twice a year to twins and it's the dad's job to care for the young while the mother recuperates. Tamarin fathers, such as the one pictured above, are known to carry their young around on their back and bring them to the mother for feeding.
Thomas Kokta/Getty Images
It’s a cold, cold world out there -- literally -- if you’re an emperor penguin chick hatching in the sub-zero temperatures in Antarctica. But these chicks have quite the devoted dad to keep them warm. Emperor penguins mate in the winter. The female lays an egg, rolls it onto dad’s feet, and then promptly takes off- leaving dad to care for the egg. Emperor penguin dads must fast for more than 100 days as they wait for their chicks to hatch. They endure extreme cold and wind, and have even been seen huddling in large groups doing "the wave" to keep warm. If mom doesn’t return in time for the hatch, the dad will produce a curd-like substance in his esophagus to feed the chick. Chicks are carried around on the parents' feet, as they depend on warmth from their parents to survive while they grow from their thin baby down to full feathers. Childcare is generally split between the two parents as they take turns heading out to sea to feed. Talk about a warm and loving dad.
Source: Smithsonian Zoo, Kevin Schafer/CORBI
Male rheas may not be loyal or devoted to one female, but they’re definitely loyal and devoted dads. Male rheas build a nest and then mate with multiple females that then lay all of their eggs together in the same nest -- sometimes amounting to more than 50 eggs. Dad is tasked with incubating and raising the young. The massive, flightless rhea is famously aggressive in guarding its brood and has even been known to attack female rheas that get too close to its young. Male rheas will keep their chicks close for about six months. It’s also common to see the chicks nesting and nuzzling into their dad’s feathers for warmth and protection.
Source: Project Seahorse, Lawson Wood/CORBIS
Seahorse dads might have it easier than most because of their unique appearance. They can camouflage with their surroundings; they have built-in pouches to carry their babies; and they even have eyes that can move independently of each other. (Remember all the times it seemed like your parents had eyes in the back of their heads?) But what makes seahorse dads some of the best in the ocean is the unique birthing process of the species. The dad is the one that takes on the burden of pregnancy. The female seahorse lays her eggs in the male’s pouch. He fertilizes them and then provides them with the nutrients they need to grow, in a womb-like fashion. Pregnancy lasts anywhere from two weeks to a month, depending on the water temperature: the hotter the water, the shorter the pregnancy. The birthing process generally takes place at night and lasts for several hours as dear old dad pushes out 100-200 babies, on average. While the young are on their own after that, we still think seahorse dads deserve to make this list for taking the wonders of childbirth off the hands -- er, tails -- of mom.
Source: San Diego Zoo, Barbra Leigh/CORBIS
While being grounded is every human kid’s nightmare, literally caging its young in a nest is part of what makes the greater hornbill such a great dad. Greater hornbills are native to Asia and prominently identifiable by their huge golden horn, called a casque. After mating with a female, the male hornbill will help the female enclose herself and their eggs in the hollow of a tree for safekeeping from predators. The male feeds the female through a small opening while she incubates the eggs. Generally, only one out of two eggs will hatch. Shortly after the chick hatches, the mother breaks her way out of the nest. But these parents aren’t done yet. With the help of the chick, they rebuild the “wall,” shutting him or her in. Mom and dad bring food by regularly, feeding the chick until its old enough to break out of the nest and live on its own.
Seahorses look like sweet, silent types, but high tech recording equipment finds that they growl when they are angry.
The discovery adds to growing body of evidence that many marine dwellers, even very tiny ones, are creatures with emotions and complex forms of communication to match. Seahorses already usually capture our attention, given their unique appearance and elegant way of moving in water.
“They are cute, monogamous and calm fish, and people usually love them,” co-author Antonio Souto of Brazil’s Universidade Federal de Pernambuco told Discovery News.
People can love them too much, however, suggest the findings, which are published in the latest issue of the Journal of Zoology.
Lead author Tacyana Oliveira, Souto, and their colleagues equipped an aquarium tank with a hydrophone to capture audio recordings of seahorses during feeding, courtship and handling by humans.
The seahorses emitted happy-sounding clicks as they fed, with males and females both clicking away during courtship. As courtship heated up, so too did the clicks, which appeared to synchronize as the females and males grew closer to each other.
When a researcher would gently hold on to a seahorse’s body near the hydrophone, though, the equipment picked up a very angry sounding “growl.” This is the first time that anyone had ever detected such a sound coming from a seahorse.
The researchers suspect that growls are also emitted when a predator holds on to seahorses in the wild.
The scientists wrote, “Seahorses are frequently grabbed and held by predators, such as frogfish, before being swallowed.”
They added, “Growls were accompanied by body vibrations, and may constitute an additional escape mechanism in seahorses, which might startle predators.”
Photo: A seahorse in the Black Sea. Credit: Florin Dumitrescu, Wikimedia Commons