Didn’t see them here when searching so how about chitons? (Class Polyplacophora)
Learned about em just recently and I’m curious as to how many people know of/have seen them!
Great choice!
Have you seen a chiton (Class: Polyplacophora)?
I have now
Yes, in photos/videos
Yes, irl
I'm not sure
Voting ended onJun 1
The species pictured are the lined chiton (found on the west coast of North America) and the blue green chiton (found on the coast of New Zealand and the eastern coast of Australia).
A neat fact about them is that several species have been found to exhibit homing behaviors, wherein they travel in search of food and then return to their home spot. There are many theories regarding how they do so, but the exact method is unknown.
Our first class of molluscs is Polyplacophora, commonly known as “Chitons”, and less commonly known as “Sea Cradles”, “Coat-of-mail Shells”, or “Suck-rocks”.
Chitons have a shell composed of eight separate plates, or valves, which overlap slightly. This allows the chiton to have protection without sacrificing flexibility, as the plates allow for some articulation and even for the animal to curl up into a ball when dislodged from rocks. The plates are circled by a skirt called a girdle, and in some species the tissue of the girdle covers the plates (image 4). Underneath the shell, the majority of the body is a muscular, snail-like foot. Gills hang down into the mantle cavity on either side of the foot. The mouth is also located on the underside of the animal and it contains a mouth with a tongue-like, tooth-covered structure called a radula. The radula is used to scrape food from rocks. Chitons have unique organs called aesthetes, which consist of light-sensitive cells just below the surface of the shell. Some species have modified aesthetes which form ocelli. These ocelli are actually quite advanced, with a cluster of individual photoreceptor cells lying beneath a small aragonite lens. Each lens can form clear images. An individual chiton may have thousands of ocelli on their back. Chitons live worldwide, exclusively in marine waters, clinging to hard surfaces. Most species live high in the intertidal zone, exposed to air and light for long periods. A few species live in deep water, up to as 6,000 m (20,000 ft) down. They are generally herbivorous grazers, though some are omnivorous and some carnivorous. They eat algae, bryozoans, diatoms, barnacles, and sometimes bacteria by scraping the rocky substrate with their radula. A few species of chitons are predatory, catching small invertebrates, such as shrimp and possibly even small fish, by holding an enlarged, hood-like front end of their girdle up off the surface, and then clamping down on unsuspecting, shelter-seeking prey (image 3).
Chitons have separate sexes, and usually reproduce externally, with males releasing sperm into the water to find the female’s released eggs. In some species, fertilization takes place in the mantle cavity, with the female then brooding the eggs within the mantle cavity. The species Callistochiton viviparus gives birth to live young. Chiton eggs have a tough spiny coat, and usually hatch to release a free-swimming trochophore larva. In some species the trochophore remains within the egg, deriving nutrition from yolk, then hatching as a miniature adult. Unlike fully grown adults, larvae have a pair of simple eyes, and these may remain for some time in the immature adult.
Chitons have a relatively good fossil record, dating back to the Cambrian. The genus Preacanthochiton is often classified as the earliest known polyplacophoran, though this is controversial and some authors have instead argued that the earliest confirmed polyplacophorans date back to the Early Ordovician. Kimberella and Wiwaxia of the Precambrian and Cambrian may be related to ancestral polyplacophorans.
How do you feel about Polyplacophora? (Remember to vote for your favorite animal within this group, not how you feel about the group as a whole!)
One or more of my favorite animals is in Polyplacophora
I love one or more of these animals
I like one or more of these animals
I am neutral about all of these animals
I dislike all of these animals
I hate all of these animals
Voting ended onDec 10, 2024
Propaganda under the cut:
There is a good fossil record of chitons, but ocelli are only present in those dating to 10 million years ago or younger. This could mean chiton ocelli are the most recent eyes to evolve.
Some species of chiton exhibit homing behavior, journeying to feed and then returning to the exact spot they previously inhabited. It is yet unknown how they do this. They may have topographic memory of the region, or they may be picking up on chemical clues from their slime trail. Their teeth are made of magnetite, and they may be able to sense the Earth’s magnetic field through them, as experimental work has suggested that chitons can detect and respond to magnetism.
Chitons are eaten in many oceanic cultures, including in Trinidad, Tobago, The Bahamas, St. Maarten, Aruba, Bonaire, Anguilla, Barbados, Bermuda, the Philippines (where they are called kibet if raw and chiton if fried), along the Pacific coast of South America, the Galápagos, South Korean islands, by First Nations people off the Pacific coast of North America, and by Aboriginal Australians.
When a chiton dies, its girdle will rot or be scavenged away, and the eight plates will come apart. These plates sometimes wash ashore and are known as “butterfly shells.”
Some chitons bear scales or needle-like spicules on their girdles which can be used for camouflage or defense:
Polyplacophora. This class is made up of chitons, marine creatures that live under rocks. Their shells are made up of eight plates, protecting them while also allowing them to flex upwards or curl into a ball.
Pteriomorphia. This subclass is made up of bivalves with large gills used for feeding and rudimentary photoreceptors. Memebrs include mussels, scallops, oysters and pen shells
tonight's invertebrates..............chiton glaucus and petrolisthes elongatus
these 2 tide pool friends have teamed up together to produce the perfect halloween costume: a green space bug alien parasite with fearsome sharp claws and badass armour plates!
with this amazing combo of polyplacophoran and decapod nothing will be able to stop them, and they will destroy all of their enemies
........spookiness rating: 84.9% better be nice to them
photographed by Emily Roberts (emily_r) (CC BY 4.0)
Chitons are one of the lesser-known members of the Mollusca phylum. They have an incredibly muscular foot on the underside of their shell that allows them to stick tightly to rocks as well as curl themselves up into a ball like an armadillo!
