Gearing up for our annual Father’s Day camping trip this weekend and wanted to give a shout-out to all Dads out there! Most people don’t think of parenting in the animal kingdom as being the best. There are only a few species, us included, that devote a significant amount of time and effort to their little ones (and it’s usually Mom taking the brunt of it!). As always, there are exceptions… check out some of these great sea-faring fathers!
There are many different types of seahorses, from pygmy seahorses (smaller than a penny) to pot-bellied seahorses (up to 12 inches), and all have Dads that actually give birth to their babies – called fry. Most seahorse fathers have an expandable pouch on the front of their bellies (kind of like a kangaroo). After the female’s eggs are fertilized, they are moved into the male’s pouch where they will stay for the next 2 to 4 weeks. The male’s pouch acts basically as a uterus. As the eggs grow, the pouch is lined with tissue and filled with a placental-like fluid; providing nutrients, oxygen, and protection. [Interesting fact: the placental fluid changes to be more like seawater before the baby seahorses are born. This eases them into the real world so the ocean water is not such a shock to their tiny systems.] Once the babies are fully formed and ready to go, the male actually gives birth to them. Dad goes through contractions for up to 12 hours and births anywhere from hundreds to thousands of offspring!
Another interesting fact: pygmy seahorses are too small to have brood-pouches; instead the males carry the eggs in a ‘brood-cavity’ within their bodies (sound familiar?) and they only have about a dozen children at a time.
A what? The yellow-headed jawfish is a small fish with a yellow head and a big mouth that lives in burrows around the edge of coral reefs. They use their big mouths for many tasks: digging and cleaning their burrows, catching food that swims by, jousting with other males, and… carrying their eggs.
When a critter uses their mouth to carry and protect their eggs it is called mouthbrooding. Many fish use this technique to provide more protection for their eggs (although most are maternal [aka female] mouthbrooders). Carrying their eggs in their mouth allows a fish to hide them and move them easily if necessary. Some mouthbrooders use their oral hidey-hole to protect their offspring even after they’ve hatched (the most well known is the African cichlid). Of course while your mouth is full of your kids it’s pretty hard to eat anything, so yellow-headed jawfish dad’s go without food for about 1 week. Talk about a crash diet!
Interesting fact: some fish take advantage of mouthbrooders and trick them into taking care of their own young. Like a cuckoo bird, the cuckoo catfish replaces another fish’s eggs with it’s own. In this case, instead of a nest, the catfish uses mouthbrooders. The mouthbrooder, usually a cichlid, will then care for the catfish’s eggs as their own offspring. These animals, like the cuckoo bird and catfish are called brood parasites.
Sergeant majors are a very common tropical fish and are identified by their black-barred bodies and a bit of yellow on their backs. These guys make nests on firm surfaces, like rocks, ship wrecks, and reef outcrops. After an exciting morning of chasing females around, sergeant majors use a kind of adhesive to stick their fertilized eggs to the nest they have prepared. Their eggs are bright red and are usually out in the open (definitely more so than mouthbrooders, huh?) and make an easy target for predators looking for a snack. It’s this Dad’s job to guard his eggs. Sergeant majors become very territorial and protective of their eggs. They will attack anything that gets too close to their precious red babies, even a diver! So if you’re diving and see one of these guys getting all up in yo’ face… you’re probably too close to his little ones.
Interesting fact: sergeant majors have three color-variations: 1 – light phase (lighter grey when swimming over open and rocky areas to blend in with the bottom) 2 – dark phase (enhance the bars on their sides to appear darker and better hide in nooks and crannies in the reef) 3 – when guarding their eggs the males turn a little blue.