Life Exceeds Expectations: Aquatic Creatures

Here are some amazing underwater animals
that go beyond the call of survival duty

Smart Octopus

Suckers for learning: why octopuses are so intelligent (The Conversation). Lisa Poncet is fascinated with octopuses. Who wouldn’t be? A doctorate in neurophysiology in France, she says that these marine invertebrates fit all the criteria for intelligence: flexibility at obtaining information, learning, storing information in memory, and applying it in different situations.

Octopus (Wiki Commons)

Octopuses also excel in discriminative learning: confronted with two objects, they learn to attack one of them in exchange for a reward, basing their choice on characteristics such as colour, shape, texture or taste, and they can retain this information for several months. They can also generalise, a complex thought process in which they need to spontaneously apply a previously learned rule to new objects. For example, octopuses who have previously learnt to attack a real ball can go on to attack a virtual ball on a screen.

A classic video of octopus camouflage given at a Ted Talk has been posted by Evolution News. The crowd gasps at the ability of an octopus to mimic not only the color but the texture of a coral mound, making itself invisible as it blends into the rock. In her article, Poncet says that cuttlefish are even smarter: “they possess exceptional learning abilities, can pick up complex rules in no time and apply them perfectly.”

Simple Sponge?

Extreme flow simulations reveal skeletal adaptations of deep-sea sponges (Nature 21 July 2021). Falcucci et al., in “Extreme flow simulations reveal skeletal adaptations of deep-sea sponges,” reveal another amazing characteristic of the already amazing and beautiful Venus flower basket Euplectella aspergillum.

Venus Flower Basket, Credit: Kesari Lab/Brown University

Scientists had already marveled at the fiber-optic-like glass rods made by this sponge that inhabits deep sea waters. Now, they have determined that fluid flows through the cone-like network of glass to maximize capture of drifting nutrients while, at the same time, preventing strong currents from toppling the sponge from its holdfast.

Our results indicate that the skeletal motifs reduce the overall hydrodynamic stress and support coherent internal recirculation patterns at low flow velocity. These patterns are arguably beneficial to the organism for selective filter feeding and sexual reproduction. The present study reveals mechanisms of extraordinary adaptation to live in the abyss, paving the way towards further studies of this type at the intersection between fluid mechanics, organism biology and functional ecology.

In the same issue of Nature, Laura A. Miller comments, “Fluid flow through a deep-sea sponge could inspire engineering designs.” Her article has beautiful close-ups of the complex mesh manufactured by this “simple” organism. And a write-up on Phys.org shows how the fluid flows through the structure. This layperson-level article also shows how what is being learned from the Venus Flower Basket could help human architectural designs from ships to skyscrapers to planes – any invention that needs to optimize fluid flow, whether water or air.

Unlikely Ecosystem Engineers

Benthic jellyfish dominate water mixing in mangrove ecosystems (PNAS). Mangrove trees play an important ecological role along many coastlines, providing good habitat for fish, turtles, birds and more animals while they protect the coastline from storm damage. But they have a problem: the water around them tends to get stale most of the time. Solution: Jellyfish! They really know how to stir up the water, and they do it expeditiously and efficiently.

Water mixing is critical for aquatic life and mangrove habitats are vital nurseries for many species. However, these sheltered habitats experience little water mixing. Cassiopea sp. jellyfish continuously produce a vertical current capable of transporting hundreds of liters of seawater per hour. They live in shallow subtidal regions and the flows they generate have the potential to result in turnover of the entire water column up to every 15 min for an average population. Additionally, Cassiopea sp. can expedite the transport of nutrient-rich water from sediments into the water column. Thus, Cassiopea sp. represent a previously unrecognized ecosystem engineer within these shallow coastal environments that can affect primary productivity and nutrient distribution and alter new habitats as their range is expanding.

With that, it’s a good time for an encore of Illustra Media’s beautiful recent film on Jellyfish, “God Doesn’t Make Junk.” Posted on 6 May 2021, it is worth watching again! After enjoying it, see more of their “Awesome Wonders” videos at The John 10:10 Project.