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[♪ INTRO]
Let’s face it. Parenting, whether it’s
one baby or one hundred, is not for the weak.
It requires a lot of time and energy to keep
babies safe and healthy.
Of course, some species take the hands-off
approach,
letting nature take its course with the next
generation.
At the other end of the spectrum there are
parents so devoted
that their offspring want for nothing.
Humans, for example, can be a great example
of that.
But there are other animals that are really
invested in caring for their young,
and these five might not be the ones you would
expect.
The tiny bromeliad crab is found in Jamaica,
living in bromeliad plants.
The plants have hollow cavities that collect
and store rainwater,
creating tiny ecosystems where these crabs
live.
They spend their entire lives there, even
raising their babies in the rainwater.
Bromeliad crabs are the only crab species
known to actively feed and care for their young
and they do it during the eight weeks the
babies spend in their rainwater nursery.
Most crustaceans only invest a small amount
of care in their offspring.
Usually that takes the form of attaching their
eggs to their bodies
to keep them safe from hungry predators.
However, researchers have found that crustaceans
who live in freshwater or on land
become more protective and provide more care
for their offspring than their marine cousins.
These environments are a lot more stressful
than marine environments,
which means a bit more parental care ensures
offspring are more likely to survive to adulthood.
Bromeliad crabs take their job as a doting
parent very seriously.
The mother crab is constantly making adjustments
to the nursery,
removing debris, keeping the water moving,
and even adding empty snail shells.
Scientists realized this behavior helps maintain
the water quality of the pool.
Circulating the water adds oxygen to it, and
the snail shells buffer the acidity and add calcium.
The mother also keeps her young safe from
predators,
since crabs are not the only occupants of
bromeliad pools.
It’s the preferred breeding site for damselflies,
whose nymphs are a common predator of crab
larvae.
Thanks to the mother crab diligently removing
damselfly nymphs,
though, her young are 60% less likely to be
eaten.
Burying beetles are members of the carrion
beetle family,
a type of beetle that makes its living, just
degrading vertebrate carcasses.
Most carrion beetles will find a carcass,
stop for a snack, lay their eggs,
and then skedaddle on outta there, leaving
their offspring alone
to hatch and hopefully live long enough to
get their snack on.
The burying beetle, however, buries dead animals
in order to care for their young inside the
carcass.
Like a lovely little corpse nursery.
These little beetles make short work of getting
a carcass underground.
A pair of beetles can get an entire rabbit
underground in just a few hours.
Once the body is buried, both parents work
to remove the fur or feathers
and then coat the skin with antibacterial
secretions,
which slows down decomposition and keeps their
young safe from disease.
But they don’t stop there.
Not only do they provide their babies with
a safe, disease-free corpse house,
they also are extremely attentive when it
comes to feeding their young.
In fact, in this respect, they behave more
like birds than beetles.
Once hatched, the beetle larvae beg for food,
and the parents respond by regurgitating food
into the babies’ mouths.
Not only is it dead animal, it’s dead animal
puke!
The larvae are actually perfectly capable
of feeding themselves;
from the carcass that makes up their nursery.
But research has shown that babies grow faster
if their parents feed them;
and both parents are happy to oblige.
The males and females both take on a share
of their parental duties,
such as feeding the babies and keeping the
carcass clean.
That’s pretty unusual behavior for any animal
species, other than human.
It’s even weirder in an invertebrate, so
researchers are still trying to work out
not only why these beetles are such great
parents,
but also why both Mom and Dad are so on board.
Fish are not exactly well known for their
parenting skills.
Many of them are not able to recognize their
own babies and mistake them for prey,
gobbling them up as soon as they see them.
Enter the discus, a tropical freshwater fish
in the cichlid family,
a fish that could win awards for the amount
of time and energy they invest in their young.
After their babies hatch, both parents tend
to them diligently,
keeping the fry, or young, very close to their
bodies.
The parents alternate who’s on duty, transferring
all the fry at once
with a well-timed flick of their bodies in
order to give each other breaks
when one parent needs to go off in search
of food.
And this is because for the first three or
four weeks of life,
the fry’s primary food source is the mucus
on their parents' bodies.
And before you go “Ew, yuck, mucus,” remember
that we mammals
are in the business of secreting a nutritious
fluid for our young, too.
Also I just told you about corpse-puking beetles.
Now mammals may have mastered this technique,
but it’s not unique to us.
After all, an easy-to-find food source that
comes straight from the parent
is a great way to aid your offspring’s survival.
Researchers took a close look at this mucus
and found that its composition changed over
time, in tune with the fry’s needs.
We see similar changes take place in mammalian
milk.
For example, around the time of birth, it’s
packed full of things
like antibodies, growth factors, proteins,
and hormones
that give babies a passive form of immunity
until their own immune system kicks in.
The fish’s mucus is also set up to pass
along immunity to their offspring.
At the same time the parents lay their eggs,
the antibody and protein composition of their
mucus bulks up.
Other cichlid fish have also adopted the strategy
of giving their young delicious mucus to eat.
However, discus are the only fish we know
of
where the parent’s mucus is required for
their fry to survive.
Multiple attempts have been made to raise
orphaned discus fry in captivity,
but they can’t eat live food, so they don’t
survive long.
Discus fish must be some super patient parents,
putting up with that constant nibbling 24/7!
Sounds awful!
Now when you consider all the places you might
put your babies
in order to keep them safe and sound, your
mouth might seem like the, like the worst option.
But in fact, about two percent of fish species
have evolved this peculiar trait
of keeping their young, or at least their
eggs, safe and sound inside their mouths.
Mouthbrooding is an extremely costly investment
in their young,
because as you can imagine, it's very difficult
to eat when your mouth is full of babies.
In the deep sea, where food resources are
extremely scarce,
scientists assumed that all fish species would
therefore take the hands-off approach,
releasing their eggs and sperm into the water
and letting them meet up and develop on their own.
That is, until researchers happened to discover
that a deep sea fish,
the parazen, is most likely a mouthbrooder.
Little is known about this deep sea fish.
To start, scientists don’t even know if
there is more than one species.
That’s what they were trying to figure out
when they discovered eggs inside the mouth
of a female specimen.
For a fish like the parazen to have evolved
this strategy is a bit of a head scratcher,
due to where it lives and how it eats.
Parazens are what’s known as winnowers:
to eat, they scoop up big mouthfuls of sand
and sift through it to find their food.
If your mouth is full of eggs, this means
that you don't eat for the entire incubation period,
or the eggs are somehow so securely attached
that eating doesn’t knock ‘em loose.
The latter is probably the case for these
fish, as these eggs were found
clumped together near the parazen’s gills
and attached by a membrane.
This finding helps to fill in some of what
we don’t know about these fish,
like the fact that researchers have never
found a parazen larva.
A mouthbrooding strategy may help to explain
why.
Scientists hypothesize that the parazen may
be investing
more energy in their young than other deep
sea fish because of where they live:
open, sandy areas that have very few spots
to hide from predators.
They might be resorting to mouthbrooding to
ensure more of their young survive
than if they were left on their own to be
spotted and gobbled up.
Many invertebrates, especially insects, have
parenting strategies
that allow them to produce a lot of offspring
over the course of their short lives.
However, this is not the case for the tsetse
fly;
a large biting fly native to Africa that’s
known for transmitting a deadly sleeping sickness.
Tsetse flies are larviparous, which means
they don’t lay eggs.
Instead, the larva hatches from an egg inside
the female fly.
Tsetse flies only produce one baby at a time,
and only a handful
over the course of their lives, which is typically
just a few short months.
A single larva develops inside the female’s
uterus,
and while it’s in there, it gets fed by
milk glands that make a nutrient-dense liquid.
Once again we’re making comparisons to mammalian
milk, and with good reason.
Tsetse fly milk transfers a lot of good stuff
to the larval fly, like beneficial bacteria,
without which females are unable to reproduce
as adults.
Once the larva is developed enough,
after about nine days, the female tsetse fly
gives birth.
The newly born larva immediately burrows into
the soil and becomes a pupa.
30 days later, it crawls back out of the dirt
as a full grown adult.
This unusual reproductive strategy sets the
tsetse fly apart from other insects,
but it ensures that their babies have a very
strong chance of surviving to adulthood.
In this case, they’re investing a lot of
effort into a single larva at a time,
rather than making lots and leaving them on
their own.
However, this also means that their populations
are slower to recover from control efforts,
unlike mosquitoes or other insects who produce
a lot of offspring.
This may help public health officials get
a handle on their populations and
control the spread of sleeping sickness, which
is especially life-threatening to rural populations.
Going the extra mile looks very different
from species to species.
Even so, all five of these creatures are lining
up for parent of the year awards.
Maybe some of you parents out there, or future
parents,
can aspire to the attentiveness of a burying
beetle!
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[♪ OUTRO]
