It’s Worse in the Water

by Rob Cooper

The vast majority of the surface of planet earth is covered by water and considering this it should be no surprise that whilst terrestrial (living on land) creatures can get rather frighteningly large, the denizens of the depths are always one step ahead. In this article I’ll examine ten of the most fearsome, peculiar and benign ocean creatures with the hope of showing just how fantastic the diversity of ocean live has been over time.

1. Dunkleosteus
Back in the Devonian a peculiar group called the Placoderms developed to truly monstrous sizes. Characterised by their armoured bodies and bony plates instead of the teeth the Placoderms reached their most terrifying in the killer whale sized Dunkleosteus. Strangely for such a large predator the 8 metre long Dunkleosteus could suck prey towards its mouth by rapidly opening its jaws (in less than 1/15th of a second). Unhealed bite marks on the head guard of younger Dunkleosteus also lend evidence to a theory of cannibalism.

2. Helicoprion
If you thought Dunkleosteus had strange teeth you may be surprised to learn far stranger tooth morphologies existed in the prehistoric seas. Helicoprion is a fantastic example of this having a ‘toot whorl’ that looked remarkably like a circular saw inspiring many strange artists’ impressions of the creature. The function of the peculiar teeth has yet to be determined but it is thought that the successive rings of teeth are analogous to growth rings in trees and that teeth successively pushed up to replace those that were lost, similar to how its modern day relatives sharks replace their teeth today.

3. Megamouth Shark
To continue from shark like animals to true sharks we next encounter a very rare modern shark colloquially known as the ‘Megamouth shark’. Since its discovery in 1976 only 55 specimens of this elusive shark have been seen or caught. Like its larger relatives, the basking and whale sharks, the Megamouth has an enormous mouth full of very small teeth that are ideal for sieving plankton from the ocean. As it follows the movement of plankton down to over 200 metres in depth it has small photophores (light emitting organs) to attract plankton and small fish to its 1.3 metre wide mouth.

4. Megalodon
It would be an insult not to mention the mightiest of all ocean predators in this article and Megalodon certainly fits that title handsomely. Well respected as the largest and most powerful predator in the history of all life (with one competitor) megalodon is now estimated at lengths of at least 14-18 metres and up to 20 metres and weights of slightly over 100 tonnes. Megalodon has the largest jaws ever discovered in the animal kingdom large enough for a full grown man to walk through without bending down and an estimated bite force of over 180,000 Newtons. This, along with other palaeontological evidence, suggests that Megalodon preyed on large whales until its extinction 1.5 million years ago.

5. Livyatan 'the great whale'
But what animal was big and ferocious enough to rival Megalodon? Strangely enough the answer comes from a contemporary of Megalodon’s the titanic Livyatan. Livyatan was a raptorial sperm whale which lived between 12-13 million years ago in the Eocene period. Akin to megalodon Livyatan remains have been found alongside those of baleen whales, sharks, dolphins, porpoises and many other sea creatures supporting the hypothesis of Livyatan being an apex predator alongside Megalodon. Unlike modern sperm whales Livyatan had the largest teeth of any animal yet discovered (bar the tusks of elephants and walrus) at up to 36cm in length. Livyatan was thought to ambush prey swimming at the surface from beneath much like the modern great white shark.

6. Leedsichthys 'monster fish'
From two rather fear inducing giants to a rather more benevolent one. Meet Leedsichthys, the largest bony fish to have ever lived. Leedsichthys ranged from around 10 to nearly 15 metres in length so probably rivaled the modern whale shark in size although a heavier bone skeleton likely made Leedsichthys considerably heavier. A strange tendency in large oceanic animals is that of eating remarkably small prey and Leedsichthys was no different and likely fed on plankton either by pumping water through its huge mouth or actively swimming to filter small organisms from the water around it.

7. Giant Manta Ray
Benevolent giants still exist today in the form of the majestic manta ray. Gliding through the waters like marine birds these gentle giants can have a wingspan of up to seven metres and weigh over a tonne. Manta’s are also filter feeders and typically herd their tiny prey into tight balls and swim through at speed with their large rectangular mouths open. On occasion Manta’s have been observed somersaulting through particularly tight balls of prey presumably to catch more prey.

8. Predator X
Leaping back 155 years to the late Jurassic period we come to a group of marine reptiles called the Pliosaurs. Pliosaurs were characterised by short necks and immensely powerful large jaws, the largest specimens having estimated bite forces comparably or far greater than Tyrannosaurus rex. Predator X was one of the largest of all Pliosaurs reaching between 12-15 metres long and possibly weighing up to 45 tonnes. Strangely, compared to modern day marine species, Pliosaurs used their four flippers for locomotion and had no tail fins to speak of; two of these fins would be used for normal locomotion whilst the other two would be used to create a burst of speed when ambushing prey.

9. Plesiosuchus
Crocodiles are often said to be living fossils and quite rightly so for modern crocodilians have hardly changed at all for hundreds of millions of years. However back in the Jurassic period, something very strange happened in crocodilian evolution… They began to adapt fully to living in the sea. At around 6.8 metres in length Plesiosuchus was one of the largest marine crocodiles and like its kin had shed the heavy, restricting armour of its forebears in favour of a streamlined body. The skull of Plesiosuchus shows many similarities to modern killer whales implying it regularly predated on large marine reptiles of the time.

10. Shastasaurus 'ocean giant'
On the topic of marine reptiles, it would be immensely uncharitable of me to finish this article without mentioning the largest marine reptile yet discovered. Shastasaurus was a primitive ichthyosaur, a group of marine reptiles that in their later stages would bear many similarities to dolphins yet the primitive forms were quite unique. The prey base and feeding method of Shastasaurus remains a mystery as it seems to have had no teeth and the suggestion that it fed on soft bodied molluscs is generally not supported by ichthyosaur skull morphology, what this strange animal was specialised for we may never know but that hardly makes it a less thrilling creature to imagine.

The oceans simultaneously offer some of the most fearsome and most benevolent creatures that planet earth has ever harboured. From gentle filter feeding giants to titanic ambush predators lurking beyond the reach of light the oceans are a place where life has fully explored the limits of size. No dinosaur has even come close to the largest baleen whales of today and whilst we may be thankful that many of their huge predators such have Megalodon have finally passed on; we do ourselves a great service by remembering just how rich the oceans are and how important they are as an ecosystem to us and other terrestrial species.

Life Without a Backbone

by Rob Cooper

It is a strange turn of phrase common today that having no backbone implies weakness and lack of stoicism. Whilst many of our most impressive contemporary animal species do have well developed backbones there are many critically important animals that lack such a feature. In this article I will attempt to illustrate and expose the diversity and nature of several extinct and extant species lacking said backbone and try to show why they should certainly glean more attention than they have until now.

1. The Colossal Squid 

A wonderfully accurately named animal, the colossal squid is the largest known invertebrate that has ever lived stretching to 14 meters and weighing up to half a tonne. Like all squid the colossal squid is equipped with arms and tentacles covered in suckers, but in contrast to the slightly smaller giant squid, this giant also has sharp hooks for catching large fish and bioluminescent squid species up to 1km below the waves. Once they are fully grown they are only predated regularly by sleeper sharks and sperm whales and still manage to give both predators nasty wounds with their hooks and suckers.

2. The Japanese Spider Crab
The largest member of the arthropod phylum (which includes: insects, arachnids and crustaceans) the Japanese spider crab can have a leg span of up to 3.8 metres and despite it’s rather fearsome appearance it is reported to have a rather gentle disposition. The crab acts as an omnivorous scavenger on the sea floor and like many crustaceans has very small planktonic larvae with transparent bodies and no arms or legs that floats in the water column.

3. The Japanese hornet
Sticking with the Japanese theme we move to a rather less benevolent creature; the Japanese hornet. The sting of the hornet reportedly induces the feeling of your flesh melting and releases a pheromone cocktail that attracts all the hornets in the local area. This pheromone is also used by hornets hunting bees. European bees, which have no defence against the hornets, are often slaughtered by the hive. Japanese bees however have learned to surround the hornet with their bodies and essentially cook the animal with their body heat. 

4. The bullet Ant
If the Japanese hornet wasn’t quite enough to freak you out I invite you to check out the infamous bullet ant. Why is it called the bullet ant? Well the sting of the bullet ant is, according to the schmitd sting pain index, the most painful of all stings and feels akin to being shot. Or if you prefer a slightly more vivid description… The sting is described as ‘waves of burning, throbbing, all-consuming pain that continues unabated for up to 24 hours’. This potent sting is thought to have evolved as a defence against predators that unearth the ant.

5. Anomalocaris
Delving back over 500 million years into the deep past a rather remarkable arthropod called Anomalocaris or ‘abnormal shrimp’ led the way in the evolution of large multicellular predators that would change the evolution of all future life. Anomalocaris was a truly gigantic animal in its time reaching two metres in length and probably preying on soft bodied organisms. The eyes of Anomalocaris like other ancient and modern arthropods were compound eyes and consisted of 16,000 lenses which represents some of the earliest evolved complex eyes able to tell friend from foe and discern environmental factors, which is clearly an incredibly important evolutionary step.

6. Arthropleura
The past often presents us with monolithic, giant versions of creatures we know today. Such is the case with Arthropleura, an ancient relative of millipedes and centipedes that stretched up to 2.6 metres in length and lived in the carboniferous period over 300 million years ago. The carboniferous period was characterised by huge amounts of vegetation and photosynthesis leading to a very high partial pressure of oxygen allowing arthropods such as Arthropleura to grow so large and is also responsible for many of earths current coal deposits hence the nomenclature of the period.

7. The Crown of Thorns 
Skipping forwards 300 million years in time, large invertebrates are still vitally important ecological factors. There is no better example than the mesmerizing crown of thorns star fish, so named for the hundreds of poisonous spines that covers its aboral (opposite to the oral, mouth containing, surface) surface. The crown of thorns feeds on coral polyps and can cause great damage to reefs if they gather en masse. However ecology is rarely so black and white. The crown of thorns provides a vital role in maintaining reef biodiversity by feeding on rapidly growing corals allowing slower growing corals to grow out and allow variance in reef composition. 

8. The Horse Conch
Fearsome snail is a term rarely used. However it is a term that perfectly describes the horse conch. A huge sea snail that lives of the coast of Florida in shallow waters up to 6 metres deep, the horse conch has made a name for itself by feeding on all manner of marine gastropods and arthropods. The horse conch has even been observed cannibalising younger members of the same species. The bright orange flesh of the animal is very striking and is perhaps a reminder of the incredibly diverse forms that even seemingly mundane animals such as snail have and do take.

9. Jaekelopterus
Sea scorpions such as Jaekelopterus were formidable ocean going predators from 460 to 248 million years ago. Jaekelopterus was discovered from a single 46cm long claw by Simon Braddy and Markus Poschmann of Bristol University in 2007. The full animal is estimated at 2.5 metres in length. Whilst not true scorpions, the sea scorpions were some of the largest arthropods that have ever existed and had the common feature of two large claws presumably used to catch prey such as trilobites that shared their primordial seas.

10. The Hagfish

The hagfish is a living fossil; that is a species that has existed relatively unchanged for a very long time period. The hagfish represents a period in evolutionary history just after the vertebrate skull had evolved but before the backbone had become prominent. The hagfish has a cartilaginous skeleton meaning it can literally tie itself in knots, and indeed does in order to provide enough force to tear chucks of flesh of whale carcasses that sink to the deep sea where it lives. The hagfish can produce huge amounts of slime on contact which increases in volume when exposed to water. This slime could be argued to be the most successful predatory fish repellent ever evolved as it clogs the gills of attacking fish preventing them from ‘breathing’. This is evidenced in how almost all known predators of hagfish are birds or mammals.

I hope I’ve demonstrated here that while many of vertebrates we see around us are certainly fascinating and incredibly important, aesthetically, ecologically and commercially, the invertebrates and strange missing links like the hagfish are not only crucially important to the working of our natural world but just as intriguing, beautiful and in some cases even terrifying, despite their disadvantage in size and complexity.