A giant water bug male carries eggs on his wings in just one instance of interesting insect parenting strategies. (Photo by Tom Murray/bugguide.net)
Sunday May 13 is Mother’s Day, and on June 17 we will celebrate Father’s Day. On these days we give thanks for the countless sacrifices that have been made to nurture, protect, and care for our development.
Many people will be familiar with the maternal and paternal behaviours of many mammals and birds. Animals such as insects, frogs, and fish also have some very interesting, and at times bizarre methods of ensuring the health and safety of their young.
In this month’s Incredible Creatures we will explore some animals that display unusual and interesting ways of ensuring there young are safe and cared for. As crazy as it sounds, some animals actually ingest their eggs or young as a means of protecting them, and we will meet an insect that quite literally sticks the childcare to the male.
Jelly, fungus and beeing a good parent
Insects such as bees, wasps, ants and termites are referred to as eusocial insects, which means they are among animals that have the highest level of organization of animal societies. One of the characteristics of eusociality is cooperative brood care. Unless you are a beekeeper you may have never seen a honey bee larvae. That is because they are permanently in the hive, and the worker bees bring them food and feed them. As the eggs hatch, worker bees add royal jelly - a secretion from glands on the heads of the bees. For three days the young larvae are fed royal jelly, then they are fed nectar or diluted honey and pollen. If, however, they are selected to be a queen, they are fed royal jelly longer to speed up their development.
Until recently it was thought that bees depend on pollen and nectar to sustain them. This is probably true for most species of bees, but a species of stingless bee in Brazil was recently discovered farming fungus to provide extra food for their larvae. The researchers at first thought the white fungus growing in the hive was contamination. But when they found it in all 30 hives they looked at, they began to suspect it was there for a reason, especially since it was growing inside brood cells – the structures that social bees build to house their growing larvae. The bees deposit regurgitated food for the larvae inside the cells, lay an egg, and the fungus starts growing. Once the egg hatches, the larva feeds on the fungus, which is absolutely crucial for their growth. When bees leave to start a new colony, they take some of the fungus with them.
Earwigs – and a rock-solid plan to keep the babies safe and warm
Some insects are classified as having subsocial behaviour based on how they care for their young. Although the level of care may not be as complete as for eusocial insects, they may still remain to guard and possibly feed the young. And some may take it a step or two further. When it is time to lay eggs, females of the European earwig, Forficula auricularia, dig a tunnel for a nest, usually beneath a stone. By choosing a site beneath a stone the female is able to regulate the temperature of the eggs by carrying them up and down the tunnel. She uses the rapidly warming stone as an incubator, placing her eggs against it when it starts to warm up, and taking them down below when the stone becomes too hot later in the day. Sometimes the male helps dig the tunnel and is allowed to remain with the female until she is ready to lay her eggs. At this point the male is ejected from the nest. The female seals the nest and guards the eggs. She is unable to feed the whole time she is guarding the eggs. While on guard the female regularly turns the eggs over with her mouthparts, “licking” them as she does this. This seems to protect the eggs from mould, and it is likely that a fungicide is applied from the female’s mouthparts. She is able to detect when hatch is imminent, and spreads them out in a single layer on the soil, making it easier for the tiny nymphs to emerge.
Get off my back
Some species of giant water bugs have interesting ways of caring for the young. As the name implies, giant water bugs are rather large insects, and their large leathery wings, which are normally held over their back, are used for more than just flying in some species. There is a group, or subfamily called Belostomatinae where the female secures the eggs on the male’s wings, and he carries them until they hatch, which is about 10 days. A male giant water bug may have as many as 150 eggs secured to his wings in a close-fitting group that almost covers the wings. Males may even stroke their own back with their hind legs to detect vacant spots. He then patiently shows her where vacant spaces are, so she can fill them in with more eggs. Although this may seem like it is adding to his burden, it is in his interest to do this. To father the most giant water bugs the most intensive use of his wings is desirable.
I’ve got a frog in my throat
There is a frog native to the forest streams of Chile and Argentina called Darwin’s frog (Rhinoderma darwinii). It is named after Charles Darwin, who discovered it in Chile during his world voyage on HMS Beagle. An interesting feature of this frog is the tadpoles’ development inside the vocal sac of the male.
The female Darwin’s frog lays up to forty eggs among leaf litter. The male guards them for about three to four weeks until the developing embryos begin to move. Then he ingests the eggs and holds them in his vocal sac. They hatch about three days later and he continues to carry the tadpoles around in his vocal sac. There they feed off their egg yolks and secretions produced by the wall of the sac until metamorphosis. At this stage, they hop out of the male’s mouth and disperse.
Darwin’s frog has undergone significant population declines due to habitat loss and degradation, largely from conversion of native forests to tree plantations. A fungal infection that affects amphibians is also a probable factor, particularly from the northern part of their historical range. The species is classified as Vulnerable on the International Union for Conservation of Nature’s Red List. A population survey from 2008–2012 found the species at just 36 of 223 previously recorded habitat sites, with small populations at those sites.
There are also many species of fish that are mouthbrooders. It can be the females (maternal mouthbrooders), males (paternal mouthbrooders) or both (biparental mouthbrooding) that take in the eggs. Cichlids are one of the groups of fish that are mouthbrooders. Some cichlids are able to feed while mouthbrooding the eggs, but others do not. Those that still can feed will feed less often than they otherwise would, and after mouthbrooding a batch of eggs, all mouthbrooding fish are underweight and require a period of time to feed and make up for the depletion of their energy reserves.
Among the cichlids and a family of fish known as arowanas, extension of brood care to the fry is common. Fry are the stage where a fish can now feed itself but have not yet developed scales or working fins. These species have behavioural cues to tell fry swimming and feeding away from the parent that danger is approaching and that they should return to their parent’s mouth. By caring for their offspring in this way, mouthbrooding fish are able to produce smaller numbers of offspring with a higher chance of survival than species that offer no broodcare.
Just like in humans, protecting and nurturing the young often requires tremendous sacrifice in many creatures, with some creative ways of accomplishing this. Have a happy Mother’s Day. And whether its watching a robin feed its young, or the bees collecting nectar and pollen, enjoy observing the many ways our wild animals care for their young.
Incredible Creatures is a monthly contribution to provide information on some of the common yet often not well known creatures that we share space with in Manitoba and abroad.