By Dr. Beth Leermakers
Some animal mothers go to extraordinary lengths to birth and/or raise their young. In celebration of Mother’s Day, let’s honor a few animal Super Moms:
Giant Pacific Octopus —
The Ultimate Sacrifice
Giant Pacific Octopuses mate only once, toward the end of their three to five year life span. About a month after mating, the female octopus (hen) lays 18,000 to 74,000 eggs (sometimes up to 100,000) that are the size of a grain of rice.
The hen hangs the eggs from the roof of her den in hundreds of strands of about 250 eggs each. The mother stays in her den for six or seven months while the eggs develop, never leaving to find food. She fans the eggs with her arms or contracts her body to shoot streams of nutrient- and oxygen-rich water over the eggs. She does this to keep them clean and free of fungi, bacteria and algae. After the eggs hatch, the mother blows the young octopuses out of the den into the open water.
The hen doesn’t eat during the 6-month incubation period. To survive, she metabolizes muscle (because octopuses don’t store fat), losing up to 50 percent of her body weight. The hen dies shortly after her babies hatch. Male octopuses stop eating shortly after mating, also losing a lot of weight. Males tend to move around in the open water without hunting or foraging, and they rarely return to their dens, making them easy prey. Both males and females ultimately die from starvation or predation.
Hornbills — Months of Elective Captivity
Hornbills go to extreme lengths to protect their eggs from predators like lizards and snakes. The mother builds her nest inside the hollow part of a tree. When it’s time to lay her eggs and incubate them, she plugs the doorway to her nest with mud and feces, sealing herself inside the tree. She leaves a narrow, vertical slit, through which the male hornbill passes food for her and, later, her chicks. The female hornbill stays trapped inside her nest cavity for three to five months while her eggs are incubating and the chicks grow up.
During their nesting time, the female and her chicks are completely dependent on the male for food. After the chicks have hatched the male may deliver food — such as geckos, frogs, seeds, insects, berries — up to 70 times per day. If something happens to the male, the whole family often dies.
Mother hornbills carry out a simultaneous molt while they’re in the nest. Shortly before laying eggs, they shed all their flight feathers at once, leaving them unable to fly. Almost all birds molt their feathers once a year, but they undergo a sequential molt. They drop their feathers one at a time, replacing them as they go so they can still fly. Because she cannot fly, the female hornbill is very vulnerable to predators (and starvation) while she’s holed up. She regrows her flight feathers shortly before leaving the nest.
Kangaroos — Magnificent Multi-Taskers
Kangaroo mothers stay busy nursing their young for almost a year and a half. After a short, 28-day gestation period, the tiny joey (about the size of a lima bean) climbs up its mother’s abdomen to her pouch. The joey then attaches itself to one of its mother’s four nipples, where it stays for nine months, nursing and growing. Then the joey emerges from the pouch but continues nursing until it’s 17 months old.
Female kangaroos (does) can get pregnant in quick succession, meaning they are nearly always pregnant. The doe mates again shortly after giving birth, but her second baby isn’t born 28 days later. This embryo develops until it’s a 70 to 100-celled blastocyst and then stops growing. When the first joey dies or permanently leaves the pouch, the embryo continues developing. This temporary suspension of development of the embryo is called embryonic diapause. It allows a kangaroo doe to carry a growing in-pouch joey while nursing another at-foot dependent joey. The doe can produce two different types of milk at once to ensure that each baby gets the nutrients it needs at that time.
Virginia Opossums (possums) — Caring for A Baker’s Dozen
Virginia Opossums are the only marsupials in North America. Like kangaroos, possum mothers keep their young in a pouch during much of their infancy. Unlike kangaroos who deliver one baby at a time, possums give birth to four to 25 joeys per litter.
After a 12-day gestation period, the mother possum delivers tiny, jelly-bean sized joeys who crawl into the pouch. In the pouch they latch onto a nipple so they can nurse 24/7. Female possums only have 13 nipples and can only feed one joey per nipple. Consequently, only the first 13 babies of a litter tend to survive.
Joeys stay in the pouch for up to two months, and then they go in and out of the pouch as they continue growing. Mom carries them on her back until they’re about four months old, when they’re able to take care of themselves.
Baby possums can become orphaned if they fall off mom’s back (she doesn’t realize they’re missing, and she doesn’t go looking for them) or if mom dies, often by being hit by a car.
If you find a possum that has been hit by a car, check her pouch (wearing gloves). If there are babies inside, leave them in the pouch and take the mom and babies to a wildlife rehabilitation center. Young possums that are eight inches or longer (excluding their tail) can take care of themselves. If you find a possum that’s shorter than eight inches from its nose to the base of its tail, you should contact a wildlife rehabilitation center.
Although they are often maligned, possums are beneficial creatures that eat ticks, preventing the spread of Lyme disease. Ninety percent of possums don’t carry rabies, and they clean up the environment by eating dead animals.
As you celebrate Mother’s Day, be grateful you’re not caring for 13 babies at once. Happy Mother’s Day!