Monday, June 13, 2016

The Best Dads in the Animal Kingdom

Paternal care is not nearly as common in the animal kingdom as maternal care, and for good biological reason. In most species, females produce fewer, larger, and costlier eggs than males do sperm. Therefore, it is usually beneficial to females to maximize the possible success of each one, sometimes by gestating them inside their own bodies (as mammals do), or incubating the eggs until they are ready to hatch (as birds do), or by providing prolonged protection, food and training until they are ready to take on the world for themselves. Males, on the other hand, are usually benefitted more by spending their time trying to mate with as many females as possible and avoiding the costs of parenting. But for some species, these costs and benefits of parenting are such that it pays for males to be good dads. Here are some of the best dads in the animal kingdom:

1. The Endurance Prize goes to the emperor penguin: Emperor penguins breed on the sea ice of Antarctica, the coldest place on Earth. After Mom lays her egg, her nutritional reserves are so depleted that she must return to the ocean (which can be over 100 miles away) to feed. This leaves the responsibility of keeping the egg warm through the freezing Antarctic winter to Dad. Dad goes months without feeding to balance the egg on his feet in subzero weather (-30 degrees Fahrenheit, on average) with freezing winds up to 120 mph, often forced to huddle together with other dads for warmth until their chicks hatch. If he moves too suddenly or the egg becomes exposed to the freezing temperatures, the chick will die. Even though he hasn’t eaten for months and has lost about 40% of his body weight, Dad provides the newly hatched chick with sustenance: a milky-type substance produced by a gland in his throat until Mom returns to the family with a belly-full of fish.

An Emperor penguin dad feeds his chick after a brutal winter without
eating a single bite himself. Photo by Mtpaley at Wikimedia Commons.

2. The Provider Prize goes to the water bug: Water bugs (also known as toe-biters) are huge, predatory, aquatic insects that can reach sizes up to 4 inches in length! They have a strong beak and a painful bite and they have been known to eat small fish, frogs and even birds! In order to grow into a large predatory insect, one must hatch from a large egg. Water bug eggs are so large that they require more oxygen for development than they can naturally absorb through the water. This requires a parent to help supply them with oxygen. However, Mom spends so much of her energy producing these humongous eggs that she doesn’t have enough energy reserves to then care for them. This leaves all of the parental duties up to Dad. In these species, Mom lays her eggs on Dad’s back in between matings. Once the full clutch of up to 150 eggs are glued to Dad’s back, he dances around and does underwater pushups to keep the water circulating and periodically takes them on a field trip to the surface for air (which has more oxygen that water does) until they hatch.

A water bug dad carries his eggs. Photo by Marshal Hedin at Wikimedia Commons.

3. The Protector Prize goes to the Darwin’s frog: Darwin’s frogs are small South American frogs that look a bit like a bloated leaf. When they mate, Mom lays her eggs in the leaf litter, which Dad fertilizes and then guards for a few weeks until the developing embryos begin to move. At that point, he “swallows” the eggs into a pouch near his throat called a vocal sac, where they hatch. He carries the tadpoles in his vocal sac until they have fully developed into frogs, at which point he “vomits” them up and they hop away to start their new lives. It’s pretty gross. Watch:

4. The Pregnancy Prize goes to the seahorse: Male seahorses have fewer (and thus more precious) sperm than males of other species and they are the only males that take on the full responsibility of pregnancy, carrying up to 2,000 babies at a time! Although they don’t have a mammalian womb and placenta, they do have an enclosed abdominal pouch specifically for the purpose of incubating the babies. Mom deposits her eggs in Dad’s brood pouch. He fertilizes them and incubates them in his expanding belly for 10-45 days (depending on the species). During this time, his body undergoes a number of hormonal and physiological changes and Mom never even makes an ice cream run for him or rubs his (non-existent) aching feet. When the babies are ready to emerge as fully developed little seahorses, seahorse dads even experience contractions as they give birth!

The best dad and grandpa in the world.
Photo by Sarah Jane Alger.
5. The Multi-Generational Prize goes to humans: Many human dads are not only good fathers, but also good grandfathers. Grandparenting is extremely rare in the animal kingdom (the first documented case of grandparenting in non-humans was as recent as 2008) and human males excel at it. They provide care, advice, lessons and resources to increase the success of their offspring and grand-offspring… It’s amazing other species haven’t picked up on this amazing secret yet!

1 comment:

  1. But for some species, these costs and benefits of parenting are such that it pays for males to be good dads. Here are some of the best dads in the animal kingdom:look at here