Cold-blooded yet caring: The reptile parents

Day seventy-three. Covid-19 crisis deepens in Bangladesh. No more sedentary, concealed lifestyle in fear of the virus. We feel bound to step out to keep up with the world. We embrace the new normals being austere and thick-skinned. To earn the bread and butter, in other words, we feel cold-blooded.  Thinking this… the thought strikes me down. What is way of life for those whose bloods are cold for real? Do they know no love or compassion – at least, for their kin? How do they survive being so 'stone-hearted'? Can we learn anything to go with the situation?

In biology, these are reptiles – snakes, turtles, tortoises, crocodiles, lizards, tuatara – that we stamped with the term 'cold-blooded'. In science, it is called ectothermy – a dependency of body heat on the surrounding weather. This sort of reliance on weather throws certain handicap. You may call it primitive, savage way. In contrast, the descendants of the slithery Basilisk, the poisonous Komodo, the feared Sobek, and the sturdy Kurma are successful for millennia, way before the way of Man. Except for the Anthropocene, the age of extinction, these primeval brutes have survived against all odds. Literally.
Today, we will look into their one mean of success: Their care of the offspring – the most sacred act ever known.

Why do they care?

Before delving further, I must clarify the basics. The standard motive of parenting is survival of the species. The standard means of doing so come with attendance and provisioning the babies. The higher the animal is in the tree of evolution, the better we see the best practices. In reptiles, the tell-tale signs are mostly subtle. But, no matter how bewildering it might sound, reptiles do invest in their young. Active instances of parental care are observed among over 1000 of species, a roughly one-tenth of total diversity.

The jaw that shatters bones can be sensitive enough to carry its young. Photo: Lori Mongano

Some do with high dedication. Dr Carl Gans, a famed herpetologist from the University of Michigan, divide reptilian parenting in three major categories: (1) investment in making an ideal nest, (2) active attention for the neonates and (3) tweaking with the incubation environment. The third category is mastered by the reptiles; they do the act with perfection.

Build the perfect nest

King cobra in its nest. Photo: Jari Cornelis

Tell me, in a world full of muck, adversaries and challenges beyond your perception, what you would do first to safeguard the offspring. Make a safe home, right? Yes. The reptiles too know the trick. With a spoonful of brain, they measure tricky calculations: robustness of materials, depth, humidity and many other parameters. Most importantly, reptiles need to predict future environs before the laying of eggs.  Best reptilian nest builders are present in all major groups.

All crocodiles do construct an ideal ground for the clutch out of foliage, mud and twigs. King cobra, the largest venomous snake, does build nest in the forest floor. Forest and river terrapins do the same. Sea-turtles does not do all the fuss. But, like all reptiles, they do know one certain special act. The nest mound does maintain an incubating temperature. The level is so fine and perfect that only certain fractional difference in temperature determines their sex. Re-think the infamous term 'cold-blooded'. Can you rather sense a sheer notion of intelligence?

Brooding: Egg attendance 

There is one group that develops this certain trait. The skinks, a type of slippery-looking, short-legged lizards, do not stop at nest making. Like birds, they become the brooder, provide ambient heat until the hatching. The grass-lizards, a legless snake-like, close cousin of skinks, are also known for brooding. King cobra and some pythons do provide similar heat by coiling around their clutch. Brooding reptiles perform one interesting act: they eat non-viable eggs and filth to stop contamination of the nest. Again, don't forget to re-think their infamy. Even, brute nature knows how, where and when to love.

The act of guarding

Five-lined skink protecting the nest. Photo: David Frymire

The next level of parental investment comes in form of vigilance. Here, crocodiles are the winner. Crocodilians vigorously protect their nesting ground. Don't be surprised to know their formidable stance for their eggs. We all know that crocs can eat anything and everything. So, they do show cannibalism. Yet, the survival instinct triggers their right senses. Mother crocs make very sophisticated parent. After burying their riverside nests, the expecting crocs wait nearby, protecting her eggs from predators or any other danger. The wait can last up to three months.

Provisioning the neonates

Perhaps, the most advanced form of parenting comes by attending the newborn. The reptiles do this too. Again, the crocodiles, the deadliest of all, stand out in the crowd. From carrying their young to bringing food to the nest ground, all details are carried out by them. A crocodilian can make multiple nests at an established territory called crèche and attend every one of them. Most exceptional of all reptiles, male of crocodiles also takes part in the caring ritual. The jaw than tear apart a zebra in seconds can be very careful while carrying the young. Male gharials, the fish-eating crocodilian, reach the height. The dominating male defends a territory, protects a group of females, attends all nests, tends the young and even let his body to be used by them as basking platform while floating in the river. Baby crocs can even vocalize to contact their parents.

A young crocodile being carried in the mouth of its parent. Photo: A Britton

Now, you see, reptiles are not as savage as they are known since the prehistoric times. When the term is survivability, they show a spectacular array of acts for their younglings. In the anthropomorphic sense, we call it love. Love enables these primitive creatures to understand and cope with nature. And, by doing these, they are thriving for ages. They might be failing in the age of extinction.

But, do we have the respect for nature that it deserves? Can we come back to our senses to tackle a more challenging world? There is much to learn from the wilderness.

Some extreme instances

Natal homing

Sea-turtle hatchlings are on their own from birth

Sea-faring turtles are undoubtedly one of the most solitary creatures on the planet. Other than a carefully chosen nest site, they don't do any other care for the hatchlings. Yet, the babies, once reached adulthood, return to the same site to complete the cycle. They outperform all challenges by passing the information genes. The act of coming to the breeding ground by the hatchlings is called natal homing.

Ovoviviparity

Sea-snakes giving birth

Many lizards and certain snakes including python, boas, and sea-snakes show a strange phenomenon. In biology, we call it ovoviviparity. It is as complex as hard to pronounce. Here, the mother retains the shelled eggs inside her body. Completely developed eggs hatch inside the womb after certain periods. This fiddly performance, however, gives many advantages. Say for sea-snakes, ovoviviparity frees them to search for a dry nesting ground in the vastness of sea.

Communal breeding

Spectacled Caiman-a communal breeder

Even stranger it may appear, few reptiles take parental care to an unthinkable peak. Many species care and share the nesting ground together. This quite astounding show by always aggressive group of animals was highlighted in a peer-reviewed study in the journal Quarterly Review in Biology. The researchers found about 481 species, including nearly 300 lizards, breed in groups. This behaviour assures extra-protection against danger.