#Chitonida

[uncharismatic-fauna]

Uncharismatic Fact of the Day

Most people fear going to the dentist, but dentists themselves bow down to the mighty chiton! These slug-like marine invertebrates have some of the strongest teeth in the world-- at least three times harder than human enamal-- and are lined with hard minerals like iron and silicate compounds which enable them to scrape minute bits of algae off of bare rock.

(Image: A gumboot chiton (Cryptochiton stelleri) by Sara Wickam)

If you like what I do, consider buying me a ko-fi!

[rattyexplores]

Chitons snuggled between the rocks for moisture

These creatures, which at first may be mistaken for barnacles or oysters, are a type of primitive mollusc, with fossil records dating back 400 million years ago.

Their appearance is quite odd, with a series of plates running down their backs, and a tough tissue surrounding them. If you were to detach one of these creatures from a rock (a very hard feat mind you), you’ll notice the underside is quite similar to that of a limpet snail.

Although the specimens pictured have a rather dull appearance, there are species of chiton that are quite colorful, like the Flame-lined Chiton.

Unidentified, Family Chitonidae

15/06/22

[drhoz]

#2420 - Sypharochiton pelliserpentis - Snakeskin Chiton

AKA Chiton pelliserpentis, and in te reo Māori papatua.

Slightly duller in colour than Sypharochiton sinclairi. Found around all of New Zealand's rocky coastlines, including the Chatham Islands, but also around the coasts of Tasmania, Victoria and New South Wales. Extremely numerous on New Zealand shores, with over 200 individuals per square metre in some areas. S. pelliserpentis generally found on top of rocks above mid tide while S. sinclari is more usually under stones and in rock pools in the lower tidal and sub-tidal areas.

Puritutu Rock, New Plymouth, New Zealand.

[dougdimmadodo]

Blue-Green Chiton (Chiton glaucus)

Family: Typical Chiton Family (Chitonidae)

IUCN Conservation Status: Unassessed

Like other chitons, the Blue-Green Chiton is a heavily armoured eyeless mollusc related to marine snails which relies on its strong aragonite-based shell to defend it from potential predators as it slides slowly along on a frilly "foot", clinging to surfaces beneath it as it travels using a layer of thin-yet-sticky mucus and the suction-cup-like shape formed by the foot's frilly rim. Although they lack any conventional eyes, the 8 armoured plates of a chiton contain numerous lens-like structures (also made of aragonite) which focus light onto a retina-like membrane, allowing the chiton to perceive light and possibly basic shapes above them in order to identify potential predators, giving them an opportunity to grip more tightly onto the surface beneath them to prevent them from being flipped over to expose their unarmoured underbelly (although if this does happen they are also able to curl up in order to leave as little of their foot exposed as possible.) Found in coastal and estuarine waters surrounding New Zealand and Tasmania, Blue-Green Chitons spend much of the day concealed in rocky cracks or under large stones and emerge at night to feed, using a spiny tongue-like structure that extends from their tiny downwards-facing mouths to scrape algae off of the rocks beneath them. The name of this species refers to the variety of colours seen on the shells of different individuals; while typically dull green, individuals with blue, yellow or pale brown shells are also frequently reported.

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Image Source: Here

Also see here for a very cool video explaining how chiton "eyes" work.

[animalids]

Conspicuous chiton (Stenoplax conspicua)

Photo by Jeff Goddard

[biojewy-remade]

Tonicella lineata

uploader: Taollan82

[astronomy-to-zoology]

Butterfly Chiton (Cryptoconchus porosus)

...a unique species of Acanthochitonid chiton that is known to occur in the Indo-Pacific, ranging from Madagascar to New Zealand. Butterfly chitons are fairly common within their range, often being seen on outer exposed rocks in areas in the low intertidal and shallow subtidal zone. Like other chitons, C. porosus is a grazer, using its radula to feed on a range of algae and other plant matter.

Classification

Animalia-Mollusca-Polyplacophora-Chitonida-Acanthochitonidae-Cryptoconchus-C. porosus

Image: GrahamBould

[drhoz]

The Great ACT-NSW-NZ Trip, 2023-2024 -Te Upoko-o-te-Ika-a-Māui

The Head of Māui's Fish - specifically, the area around New Zealand's capital city, Wellington, deriving from the legend of the fishing up of the island by the demi-god Māui. The harbour is the mouth - an area of reddish-purple rock facing onto Cook Strait was the bait Māui used.

Wellington's placement makes it one of the windiest cities in the world, and the narrow strait and howling gales makes for complicated tides and a shocking number of shipwrecks. The geology makes for some fun times too - the Haowhenua (Māori for 'land swallower') earthquake around 1460 AD raised the harbour area by 6 meters, turning some islands into the Miramar Peninsula. The 1855 Wairarapa earthquake moved a 150km stretch of the Wairarapa fault 20m along and 8m up. in some respects this was convinient timing, since the city had been desperately short of flat land at the time, and now part of the harbour wasn't harbour anymore. It's now the central business district of the city.

Every public building in New Zealand we went into had a warning plaque that the building was earthquake prone - one of the museums in wellington had that, BUT also suggested, if the quake was a particularly big one, you might want to head to the top floor rather than out into the street. Because Wellington is also tsunami prone. The 1855 quake produced one that reached 11m above sealevel.

The hills are also festooned with delightfully eccentric architecture, and more than a few funicular lifts so people can actually get to their homes from street level. One person had a funicular installed because their dog was getting elderly and struggled with the stairs.

Most of the species I saw were along the shoreline - at the harbour and ferry terminal in the city, out around the edges of the Miramar Peninsula, and out on Cook Strait at Pariwhero/Red Rocks.

The geology at Pariwhero is quite interesting - much of the basement rock in New Zealand is greywacke, a dark sandstone derived from turbidite deposits acculmulated at the edge of the Australian tectonic plate. At Pariwhero there are also deposits of argillite, a finer-grained rock quite useful for stone tools. And basalt - but the volcanic rocks are 50 million years older than the greywacke and argillite surrounding them. That's because the basalt was originally a set of seamounts - underwater volcanoes - scraped off the Pacific Plate as it subducts under what would one day be New Zealand, buried 10-15km deep, and pushed back to the surface again as more and more stuff gets piled up on the accretionary wedge and the entire area gets folded over double and concertinaed. Most of the colour in the local rocks is the result of iron leaching out of the basalt over tens of millions of years, and the argillite was deposited in the lee of the seamounts.

[drhoz]

#2419 - Sypharochiton sinclairi - Blue-ringed Chiton

AKA Chiton sinclairi.

Chitons are also called coat-of-mail shells, sea cradles or suck-rocks, or more formally as loricates, polyplacophorans, or polyplacophores. The name chiton is Latin derived from the Ancient Greek word khitōn, meaning tunic (which also is the source of the word chitin). The Greek-derived name Polyplacophora, for the Class, means 'many tablet bearing', in reference to the chiton's eight shell plates. These plates, known as butterfly shells once the chiton dies, are surrounded by a fleshy muscular girdle which may be armoured with granules or scales, as here.

The blue-ringed chiton is endemic to the North, South, and Stewart Islands, and also recently recorded from the Chathams. There are at least 900 species worldwide, and a good fossil record dating back to the Cambrian.

Polyplacophorans are grazers on algae and other encrusting organisms, and are well-known for their ability to return to their home position as the tide retreats. It's not clear how they navigate, but it may be related to the magnetite that coats their teeth. If dislodged from the rock (difficult, given their powerful grip) many can curl up for protection.

They have thousands of light sensitive organs scattered over their shells - in some species these have aragonite crystal lens and are true eyes. Surprisingly, these eyes only seem to have evolved in the last 10 million years, making them by far the most recent version of the organ.

Chitons have separate sexes, and fertilization is usually external. Some species brood the eggs within the mantle cavity, and the species Callistochiton viviparus gives birth to live young.

Some species are eaten by humans. Other predators include seagulls, sea stars, crabs, lobsters and fish.

Puritutu Rock, New Plymouth, New Zealand.

[animalids]

Rosy slender chiton (Stenoplax fallax)

Photo by Marlin Harms