The forgotten fish?


Shark finning is a massive, multi million dollar industry. But there’s another fish that’s more endangered (in fact, the IUCN once described this as one of the most endangered species on earth) that’s also being killed illegally for one small component of its body. Above is the beluga, or Huso huso. Not the whale, but the sturgeon. Growing up to some massive sizes of 1500 kilos and 7.2 meters long (as one specimen caught in 1827) and living for up to 100 years it is also the oldest living family of bony fish. It is hunted for its roe. Beluga caviar is one of the most exclusive and sought after types of caviar, and severe overfishing has caused this beautiful fish to be classified as critically endangered by the IUCN.

Beluga caviar can sell for as much as 10,000$ per kilo depending on the quality, with a special sort (harvested exclusively from females at least a 100 years of age) going for some 25,000$ per kilo.

Much like the shark, the beluga is an apex predator in its environment, and it would be a shame to see such a beautiful fish disappear.

That was a very ocean concerned episode of family guy. I rather liked it.

Just thought i’d also showcase some of the beautiful drawings by Ernst Haeckel of radiolarians and diatoms (left and right respectively).

While we’re being microbiologists, lets also explore the zooplankton. These are radiolarians, they are, if possible, even more intricate and beautiful than diatoms due to to their mineral based skeleton. The feeding manner is quite interesting: Using extensions in their skeleton known as pseudopods, they slowly ingest prey such as diatoms or other small plankton. In some cases however, they have been found to be attached and slowly digesting zooplankton sometimes 1000x larger than themselves (which still isn’t that large, as radiolarians only grow to a max of 300 microns, but still an impressive feat nonetheless)

Things in the ocean that you can’t see, but really should be paying attention to:

Diatoms. One of the most commonly found types of phytoplankton, they’re made up of these incredibly complex silica exoskeletons, which give them their distinctive look. They’re an incredibly important group - alone they’re responsible for something like 40% of marine primary production.

5 things you may not have known about the ocean. 1. While its commonly known that the ocean covers something like 71% of our planets surface, it contains within it 99% of the habitable space on earth. Within this 99% as much as 95% of the life on earth is found.   2. 90% of the ocean is considered “deep” (over 2000 meters) and the average depth of the ocean is around 3795 meters. The deepest point (the Challenger Deep) is 10,916 meters. That’s as much as 1.23 Mount Everests. The pressure of the water on top of you at this point is equivalent to supporting 50 Jumbo Jets by yourself.   3. Only 10% of the sea has been explored by humans. In this 10%, around 200000 species have been described: it is estimated that as much as 30 million species may remain undiscovered.   4. The largest animal ever to live on this earth is the Blue Whale, measuring in at 30 meters long and weighing 180 tonnes (although the Bootlace Worm can grow longer than a blue whale, with some being measured at 50 meters long and 10 cm wide). It is also one of the fastest aquatic animals, reaching speeds of 50 km/h (the fastest are Sailfish, clocking in at 110 km/h)   5. The ocean is being destroyed at an alarming rate: More oil reaches the oceans as a result of leaking cars every year than the BP spill, and as much trash is dumped in the oceans each year as fish are taken out. Around 100 million sharks are killed yearly, 30% of these for their fins and the rest as by-catch.

5 things you may not have known about the ocean.

1.

While its commonly known that the ocean covers something like 71% of our planets surface, it contains within it 99% of the habitable space on earth. Within this 99% as much as 95% of the life on earth is found.

 

2.

90% of the ocean is considered “deep” (over 2000 meters) and the average depth of the ocean is around 3795 meters. The deepest point (the Challenger Deep) is 10,916 meters. That’s as much as 1.23 Mount Everests. The pressure of the water on top of you at this point is equivalent to supporting 50 Jumbo Jets by yourself.

 

3.

Only 10% of the sea has been explored by humans. In this 10%, around 200000 species have been described: it is estimated that as much as 30 million species may remain undiscovered.

 

4.

The largest animal ever to live on this earth is the Blue Whale, measuring in at 30 meters long and weighing 180 tonnes (although the Bootlace Worm can grow longer than a blue whale, with some being measured at 50 meters long and 10 cm wide). It is also one of the fastest aquatic animals, reaching speeds of 50 km/h (the fastest are Sailfish, clocking in at 110 km/h)

 

5.

The ocean is being destroyed at an alarming rate: More oil reaches the oceans as a result of leaking cars every year than the BP spill, and as much trash is dumped in the oceans each year as fish are taken out. Around 100 million sharks are killed yearly, 30% of these for their fins and the rest as by-catch.

A Nudibranch laying an egg spiral on a Polycarpa aurata sea squirt.

A Nudibranch laying an egg spiral on a Polycarpa aurata sea squirt.

Irrelephant wanted some information on Sea Squirts/ascidians, so here we go. Prepare for some proper marine science.

I think ascidians are actually somewhat ignored, they’re some very beautiful animals. Consisting of around 2300 species it’s quite a diverse class although they all have some common characteristcs: They’re all sessile (attached to a hard substrate), they’re all filter feeders (meaning they filter out organic matter from the water column) and unlike other similar Tunicates they have a much tougher tunic made of polysaccharides. They can either be solitary or form colonies several meters in diameter. They have a relatively simple nervous system, with receptors for chemical changes, light and touch. All are hermaphroditic and capable of both asexual & sexual fragmentation. 

Interestingly, Nudibranchs (amongst other animals) feed on them, but also use them as a substrate for egg attachment. 

Due to the incredible filtering capabilites of these animals, they’re incredibly sensitive to pollution.

As for some interesting species, Polycarpa aurata and Rophalaea are incredibly pretty, but Didemnum (shown above overgrowing green algae) species might be more interesting due to it being a major invasive species (and only one of the many invasive sea squirts) and generally a big nuisance.

5 Favourite Cephalopods, No. 4:

The Blanket Octopus, Tremoctopus is not actually a single species but a genus of 4 different species: Tremoctopus gelatus, robsoni, gracilis & violaceus, with T. violaceus being the most common one. 

Blanket Octopus females may grow as large as 2 meters, while males achieve a measly 5-6 cm. They’re also immune to the Man o’ Wars poison, and while they don’t predate on it, young octopus may rip off tentacles and use them for defence. Beautiful thing.

a 1964 US Air Force instructional video on how to defend yourself against sharks. Rather amusing.

Sharks populations are declining worldwide. This is (somewhat) common knowledge. What i think escapes most people is how important sharks are to the marine ecosystem.

In all marine food chains where there are sharks, they are at the top. Now, you remove the shark, you’re cutting of the head. There would be nothing to regulate (except human overfishing, but that’s another matter for another post) fish which feed on phytoplankton down at the bottom off the food chain. This phytoplankton creates something like 70% of atmospheric oxygen through photosynthesis. 

It’s amazing how sharks, who managed to survive all 5 major extinction events in this planets history are now finally disappearing. Who needs asteroids and massive volcanic eruptions when we have ourselves? 

5 favourite Cephalopods, number 3:

Of cephalopods (and aquatic animals), there is one who’s beauty and presence can’t be denied: Enteroctopus dofleini, The Giant Pacific Octopus. Weighing in at between 60-70 kg and with an impressive length of up to 4 meters, it is the largest of the octopus (sharing the title with the 7-armed octopus). It is an incredibly intelligent creature as well, octopus is one of the few creatures which you are not allowed to perform surgery on without anaesthesia.