Imagine there lives a serpentine alien species on a hospitable terrestrial planet in a galaxy far far away, they are found around the swampy area and the entire place will become waterlogged during night fall. The moon always cause high tides at night time and the serpentine alien must evacuate their habitat to escape the rising acidic sea water (worst ocean acidification ever). Once the water retreats in the morning, it leaves behind plenty of nutrient for the alien to feast.

My question is how does the limbless 3m serpentine alien moves a dozen ping pong sized eggs to a higher place such as a tree?

Notes, not rules:

  • The "snake" only lay a dozen eggs once in their lifetime
  • They risks being hunted by diurnal predators with flying capability(edited)
  • They look and moves exactly like their Earth counterpart, boa constrictor.
  • They need to hide themselves by burrowing underground since all the vegetation including the trees are nigh indestructible, at least no alien can break or eat them.
  • The eggs grow spikes over time resembling sea urchins, each needle contains a chemical that can induce deadly allergic reaction to all alien including themselves.
  • Eggs should never be allowed to come into contact with the sea water.
  • I am thinking super hard for a solution that can protect the eggs from the occasional flooding, but i want the alien to exhibit a parental behavior at least until the egg hatches.
  • So they will have to shift the eggs themselves and I strongly believes that they must have evolved a unique trait for that.
  • You need to give a real life example of the behavior or traits stated in your answer.
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    $\begingroup$ I'm not a biologist, but I would think that the trait "the young cause allergic reactions in their parents" would not last long due to natural selection. $\endgroup$ Commented Dec 11, 2023 at 13:59
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    $\begingroup$ @MichaelSeifert Actually, if the species would produce only one batch of offspring in their lives anyways AND IF the offspring were capable of fending itself and reach adulthood after their parents died of nominal allergic reaction then that trait would not put anymore pressure on the species. $\endgroup$ Commented Dec 11, 2023 at 14:58
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    $\begingroup$ why would they lay eggs on ground and not in the trees? $\endgroup$
    – John
    Commented Dec 11, 2023 at 20:51
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    $\begingroup$ @MichaelSeifert I would think that the trait "the young cause allergic reactions in their parents" would not last long due to natural selection -- yet, human race seems to have managed to continue for several millenia, despite the existence of teenagers :) $\endgroup$ Commented Dec 11, 2023 at 20:52
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    $\begingroup$ Why would they lay eggs only once in their lifetimes? Any others who would lay eggs multiple times, would outcompete them. $\endgroup$
    – vsz
    Commented Dec 12, 2023 at 7:18

7 Answers 7


The simplest solution is for them to lay their eggs into a cavity in the tree, high above the tide range, and roam around the nest to protect them until the eggs hatch and the offspring is born.

If the tides happen every night, carrying the eggs around twice a day meaninglessly increase the risk of losing/damaging them, and considering the creatures only lay 12 eggs in a lifetime that risk seems too high.

  • 6
    $\begingroup$ Actually, because of the way gravity works there are two high tides each day, meaning the eggs would have to be transported 4 times a day: twice up, twice down. If the moon has enough gravity to create a high tide when it's directly overhead, it also is creating a high tide on the far side of the planet at the same time. $\endgroup$
    – AndyD273
    Commented Dec 11, 2023 at 18:32

So they need to haul their eggs twice every day, but will die of a lethal allergic reaction if they touch them, right?

They use the bag.

(A fancy snake skin bag). All lizards molt from time to time. The molted skin is usually dry and very brittle.

Once in their lives, however, these creatures go through a specific type of molting, during which they shed one especially thick and durable skin. This happens right before they lay their eggs, which they do inside the skin.

If they need to move the eggs, they move the entire skin full of eggs by holding it in their mouth.

The skin can have natural camouflage, a neutral smell (or have an aposematic pattern), and/or it can retain some nutritional value for newly hatched creatures to feed on.

Edit: As for real life example. Some spiders tends to carry their egg sacs around.

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    $\begingroup$ So, are marsupial serpent? $\endgroup$
    – Bergi
    Commented Dec 13, 2023 at 16:03

Terrestrial snake eggs are laid and are often stuck together in a single mass, though not solid they fall apart and separate easily.

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Your creatures eggs are laid together to form a cohesive ring, or shield shape that will fit snugly around the neck of the creature, when she wishes to move them. This mass is held together by a resin like excretion from the mother. With a special muscle, the female is able to expand and contract her body within the shape to hold them firmly as she travels up and down the tree. The protective spikes on the eggs are only on the upper side of the eggs so she is able to transport them.

As an added benefit of this behavior is that the "egg shield" protects the mother from attack wile she moves them about.

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    $\begingroup$ I think no species would use it's eggs as shield or weapon (even with spikes), but the spikes make the spot less favorable to being attacked while the mother is encumbered $\endgroup$ Commented Dec 12, 2023 at 8:26
  • $\begingroup$ @ChrᴉzremembersMonica From an standpoint of evolution, what is more important. A batch of eggs or the mother that can produce several batches of eggs? That said, the fact that the eggs protect the mother isn't the point of the method I put forward, just an evolutionary side effect that would reinforce the behavior. $\endgroup$
    – Gillgamesh
    Commented Dec 13, 2023 at 16:33

As mentioned already, the simplest and most reliable method is laying the eggs in the right spot, keeping the eggs inside the mother until the right spot is identified or built. Other options :

After the nest is completed in the tree, the creature might carry the eggs one at a time in the mouth like mouthbreeding frogs or fishes.

Assuming they move like boa constrictors but the ribs and muscles are smaller and tighter, then the skin/scales could hold the eggs as the creature moves and ascends. Like rolling a coin over knuckles, but the knuckles are inside a thick glove.

Change the egg structure a bit from the description, so that delicious stuff grows between the spines. A predator picks up the egg, moves it, and eats the easy good stuff, then leaves the spiny hard core where it's dropped, to hatch later.


Because of the spikes the snakes can't incubate the eggs with their body heat, which means that they'll need a different source of heat. The easiest source is sunlight.

Likewise, because of the spikes something like an evolved specialty pouch doesn't work.

But if the eggs had a sticky coating the mother could climb up into the tree high above the canopy where the sun would get filtered out, and lay them on the bark in a place they would get the most sunlight. If the eggs were patterned to match the bark then it would be harder for predators to see them, and once they grow the spines they would be very hard to get at.

Being up high has another advantage in that the baby snakes would hatch out of their eggs, and then fall clear of the spikes, meaning that they wouldn't risk getting poisoned staying in a nest with the discarded egg shells.

The parents could either stay near by the eggs when they aren't hunting for food, especially in the time before the spines grow, but again because of the spines they can't get close enough to do much other than that.

They could also stay below where the eggs are hatching to ensure that nothing tried to attack the new baby once it falls down from the tree.


If you really want the snakes to do the full incubation thing, Another way would be for the snakes to create a nest in the tree, lay the eggs, and then cover them with vegetation. The spines would grow in, but there would be a layer of protection between the eggs and the snake, meaning they could incubate the eggs safely.

Unfortunately I can't think of a way to allow the snakes to move the eggs in a manner that would actually keep them safe, and not put them into more danger while transporting them.


I think the safest way to keep the eggs from the acidic seawater and to move them around is within their bodies. As in to keep them inside until they are ready to hatch and give birth to live young. As long as the adult snakes are safe from harm and survive the eggs should also be safe from acidic sea water and predators and wont be visible as a target.

Apparently anacondas which is very boa like and 6 other species of snake that give birth to live young.



The snakes swallow the eggs and excrete them up the trees. If the distance is to big, they can crawl with the eggs in there stomache. The eggs are protected against that environment and the poison does prevent the excretion of diggestive tract juices. Instead a sort of glue is excreted, that hardens in contact with air, allowing for the eggs to be glued to the tree branches.

Also observed is snakes of the same family, forming a pipeline of eating and excreting eggs, to bring them to the "family" tree.


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