Echinodermata! Starfish! Sea Urchins! Sea Cucumbers! Stone Lillies! Feather Stars! Blastozoans! Sea Daisies!
Marine invertebrates found throughout the world's oceans with a rich and ancient fossil legacy. Their biology and evolution includes a wide range of crazy and wonderful things. Let me share those things with YOU!
Given its proximity to Halloween and my propensity for sharing cool stuff about weird animals my post this week is about one of my favorite bizarre sea slugs: The ones in the genus Melibe!
Melibe (in the family Tethyiidae) includes 17 currently recognized species which are known Primarily from the tropical and temperate Pacific but with a minority of species from the Atlantic, including South Africa and the tropical west Atlantic (Bahamas, Florida, etc.)
Personal caveat: I am not an expert in nudibranchs and have gone with names used by the photographers. If you know better let me know and I will correct them.
Here's a "classic" Melibe leonina from the California coast to give you an idea of what the general body plan looks like...
What you are seeing in the picture below is its digestive glands!! The body is completely transparent!! This species was originally described from Malaysia. These images are from Lembeh (Indonesia) and other images have been identified from the Philippines, so I would imagine it occurs in roughly that tropical, central Pacific region.
This one from Lembeh, Indonesia. This one is also identified as Melibe viridis, but which seems to vary somewhat from the one from Japan. These can get quite large with some individuals reaching almost a foot long!
Although many of these are essentially common names, they are surprisingly standardized and are widely recognized in addition to the western Latin names. While studying these I also encountered a few other cool stories about invertebrates which have been part of Japanese folklore and myth.
So this week: The Invertebrate-Japanese folklore connection! Names & monsters/spirits inspired by invertebrates!!
The spines on the head are a characteristic feature of this yokai. Its this characteristic which has most likely been lent to Acanthaster planci, the crown of thorns starfish which is known in Japanese as the Oni Hitode or "Demon starfish" 鬼ヒトデ
Here's another kawaii I found of the Oni-hitode, which from what I understand was part of a"Kill the crown of thorn starfish" campaign. Acanthaster planci, is a fairly well known predator of coral and has been undergoing massive population booms leading to frequent efforts to remove them.
Higuruma is apparently one name for a ghost/yokai called Kasha (whose name apparently translates to "flaming chariot" who carts the corpses of sinners off to the underworld (thanks to Matt Alt for this info). I suppose in this case the "corpses of sinners" are represented by small crustacean prey! Muahaha!
The resemblance between the flames (the arms) emerging from the wheel (the disk) is how this starfish was likely named! Pretty neat!
Image from Dr. Fujita
To give you a better idea, here is a very similar "fire wheel" type yokai called Wanyudo, which translates to "wheel monk" and who apparently steals the souls of those who gaze upon it. Apparently many yokai can be similar in appearance
It also shows the "flames from wheel" appearance that this starfish takes after...
Image via the Yokai Attack! FB group
Interestingly, Higuruma hitode was actually assigned to a similar species called Novodinia pacifica so perhaps Brisingaster robillardi should be referred to as a Wanyudo hitode or perhaps a Kashahitode??
3. The Sazae-oni aka the "Snail Ogre" 栄螺鬼
This yokai is apparently one of the more malevolent ones and according to Yokai.com is a dangerous spirt that pretends to be a beautiful drowning woman in order to lure and feed on sailors.
These yokai are actually based on horned turban snails, Turbo cornutus which look like this
These snails in Japan are called sazae (hence the name "snail demon"and are eaten throughout Japan, often grilled in their own shell
This species of snail is widely familiar to the Japanese and was even made into a kaiju called Gogo in the show Ultra Q, the precursor to Ultraman!
4. Hekigani ヘイケガニ The "samurai crabs"(the crab Heikeopsis japonica) This "ghost" is actually more of a ghost story. It basically relates the story of this crab, Hekeopsis japonica which often have a very human-like face on their carapace (i.e., the top side of the skeleton).
This crab species was also made famous by Carl Sagan who discussed them as an example of inadvertent character selection on Cosmos. You can watch this segment here
4a. The Kani-Oni: DEMON CRAB!!
While doing research for this post I came across this creature, the Kani oni! aka the Crab Demon. I couldn't find out much about it, but I did realize one thing..
Thereare only THREE pairs of legs per side. This is a characteristic feature of lithod crabs, which are actually more closely related to hermit crabs. "Proper crabs" such as the Japanese spider crabs have 4 legs on each side.
But this species is very similar to this species, Lithodes aequispina (unconfirmed ID). Thus, the ghost crab does seem to be something in the Lithodidae.
The spines on the crab might allude to another species of lithode crab which has bigger and more prominent spines on the carapace, such as this one.
5. TheUmibōzu 海坊主
So this particular ghost isn't actually based on an invertebrate..but it gets honorable mention..
The name Umibozu translates to "Ocean or Sea, Buddhist Monk" and have been explained as the ghosts of drowned buddhist monks. They are apparently haunted spirits of the ocean and mentioning their name invokes bad luck for ships at sea.
From all the accounts that I could find, there are apparently different "morphotypes" of what Umibozu look like with some images looking a bit more of a human shape...
The Umibozu tend to be rarely seen and considered somewhat mysterious..
I happened to notice a curious coincidence between these and Opisthoteuthis, aka one of the "dumbo octopuses"! But nah.. the umibozu are FAR more menacing!
ATTENTION all photographers, divers, bloggers, scientists, natural historians, citizen scientists, museums, zoological parks, aquaria, big ocean organizations, and other colorful mollusk enthusiasts (in no particular order)!
Let it be announced herein that October 29th of this year (Updated: Saturday-2016) will be SEA SLUG DAY!! #seaslugday
Sea hares for example are actually a distinct group from nudibranchs. But they are often regarded as "close" to nudibranchs.
So, to avoid "nudibranch VS. sea hare" or "nudibranch VS. sacoglossan"arguments and etc. I'm just going with "sea slug". For the biologists out there: No, its not monophyletic. But its an easy catchall term. and the hashtag is slightly shorter than "nudibranchday".