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Kidadl Team

AUGUST 06, 2021

Crinoid: 15 Facts You Won't Believe!

Learn many interesting and attractive crinoid facts here.

Crinoidea is a small group of echinoderms that live in the deep sea. They have two bodies, the calyx and the rays, and they feed on algae. Their body is very spiny since they are echinoderms and they have anus is located on the outer surface of the mouth, and the mouth is usually open. They usually show radial symmetry. The rays extend from the calyx and are attached to the ossified cone in a cup shaped structure. They have flexible anchor called cirri. Also, some deep-sea crinoids have a third body part, the stalk. This structure is composed of stacked calcite disks. A stalked crinoid has a central skeleton that is composed of calcitic ossicles and calcareous plates. This structure provides support and protection. The tube feet which are u shaped of a crinoid are used to move food particles down a ambulacral groove.

The rays are also important for swimming. By controlling their body's contraction and relaxation, they can swim smoothly through the water. The crinoid's internal organs are responsible for digestion and reproduction. The calyx is home to the entire digestive system. The coelom, which is extended into the rays, is also located in the calyx. When the sea lilies or any other crinoids breed they give raise to the larvae called doliolarian larvae which develops into young crinoid. All but one of the subclasses of crinoids is extinct and only one of the surviving subclass is known through its fossils. There are over 600 species of crinoids that still survive today. They are descendants of the crinoids that survived the mass extinction at the start of the Permian period. Crinoid fossil ages million years found near the sea rocks and sometimes on the sea floor.

For more relatable content, check out these jellyfish facts and catfish facts for kids.

Crinoid Interesting Facts

What type of animal is a crinoid?

Crinoids are the marine creatures like sea lilies, feather stars and comatulida.

What class of animal does a crinoid belong to?

Crinoids belong to the phylum echinodermata and class Crinoidea.

How many crinoids are there in the world?

All but one of the subclasses of the crinoids are now extinct. Their fossils are only known through spectacular fossils. Fossil crinoids are some million years old and are of high value for the taxonomy and fossil record. There are 5000 species or crinoids known in the world including the fossils in the fossil record, many fossil crinoids extinct by the end of Permian, and some 625 living species are known to this day and are endangered species like the sea lilies and feather stars.  

Where does a crinoid live?

The crinoids  live in deep ocean trenches, which are usually located at depths of over 3,935 feet. They require little or no energy to maintain their bodies' energy needs.

What is a crinoid's habitat?

The crinoid habitat is mainly found in Grand Bahamas islands, marine regions of North America and Australia at the great barrier reef with a lot of diversity and also across Japan and West Indies. Most of the fossil crinoids are found in Paleozoic rocks are disk-shaped plates.

Who do crinoids live with?

Crinoids live in colonial groups with the other crinoids and also with living crinoids and living species  like sea urchins, sea feather, brittle star and more the fossil crinoid is found underneath the rocks also colonialized.

How long does a crinoid live?

Paleontologists believe that the crinoids, which are large animals that lived in the oceans for at least 485 million years ago, are the earliest known creatures. Crinoids are the oldest known fossils. They first appeared in the seas around 300 million years before dinosaurs. They live million years and later as dead fossils.

How do they reproduce?

The crinoid species have gonads located in the arms, while others have them in the genital canal. The gametes produce their sperm and eggs in the enclosed genital coeloms across their arms. In certain genera, the eggs are fertilized using secretions from the epidermal glands.  The eggs hatch and produce free-swimming vitellaris. The larvae have a barrel-shaped body with cilia running around its body. It is a non-feeding member of the echinoderm subclass. The lineage that lost its feeding stage during the Permian extinction is believed to have passed down from that time. The free swimming larvae are called the  doliolarian larvae.

What is their conservation status?

The crinoid fossil meaning the dead fossil that is intact and preserved  or conserved in museums for its high value in studying the fossils. These species have living organisms deep under the sea that lacks any human intervention, and they are well fledged and protected under their own environment. Their conservation status currently is Not Extinct.

Crinoid Fun Facts

What do crinoids look like?

Sea lilies are very attractive to the eye and are part of a subclass known as Crinoidea. Their main body is composed of a slender, extended stalk that's attached to a simple, rootlike structure. They are in delicate shades of yellow, pink, or red. Adult crinoids have the mouth on the upper surface. Their feeding arms are surrounded by a U-shaped gut. The anus is located on the oral disc near their mouth.

Crinoids appear like a colorful, blooming flower under the sea.

How cute are they?

These fish are cute, as they appear like plants, and are found in attractive colors which are admirable to watch.

How do they communicate?

Most modern crinoids are free-moving and lack a stem. They can also swim by crawling or using the cirri as legs. In most cases, a change in the current direction or an encounter with an individual can induce a movement that is similar to swimming. They usually communicate flapping their arms across the water currents and all their five arms act like the bristles across the predating and giving signals with the movement of the stem along the arms.

How big is a crinoid?

Most crinoids are free-swimming and have a vestigial stalk. In deep-sea species, which still retain a stalk or crinoid stem, it can grow up to 1 meter long. They are as big as thrice of an octopus.

How fast can a crinoid swim?

The fastest moving stalked crinoid was recorded in 2005. It was moving at a speed of about 0.6 meters per hour.

How much does a crinoid weigh?

A living crinoid weighs about 27 oz (746 g) . Where as the crinoid fossil weighs about 0.06 oz (1.760 g).

What are their male and female names of the species?

No, the male and female species of crinoid do not have different names but the class has may species with different common names like sea lilies and feather stars.

What would you call a baby crinoid?

The larvae of the crinoids are called the  doliolarian larvae which can also be called their baby or undeveloped adult crinoid.

What do they eat?

These crinoids filter the water so mainly they are the filter feeders and they eat decaying matter that is detritus, around them by holding their arms perpendicular to the current. They then move to a certain location to maximize their feeding opportunities. Their flexible arms are raised to form a fan-shaped structure. Their primary tube feet are used to catch the food particles. The crinoids' feet are covered in sticky mucus that traps the particles that enter their bodies. These animals then flick the food particles into the ambulaccaral groove, which propels the mucus and the particles into their mouths. The length of their bodies can vary significantly. The mouth slides into a short position. The intestine then flows into a short muscular rectum, which opens into a small conical protuberance. This is followed by a drop of mucous-cemented pellets.

Are they dangerous?

No, the crinoids are not dangerous to human, as they do not cause any harm in any way.

Would they make a good pet?

They are usually very deep under sea in all dark, so they do not make a good pet.

Did you know...

In 2012, geologists isolated organic molecules from 340 million-year-old fossilized crinoids. These molecules are the oldest known components of the crinoids. These fossil fragments can serve as the primary supporting structures for the clasts in sedimentary rock.

How did crinoids go extinct?

Two periods of abrupt adaptation radiation occurred in the crinoids. The first was the Ordovician, and the second was the early Triassic. Two periods of abrupt adaptation radiation occurred in the crinoids. The first was the Ordovician, and the second was the early Triassic. During the Ordovician, flexible arms were widespread, and this radiation was triggered by predation pressure. By the end of the Cretaceous, most crinoids had already become extinct, and the only ones that remained were blastoids. Crinoid stem fossil age are to have been attached to floating driftwood. These creatures then live in colonies that are often found. Pentacrinites have a stem that can be several meters long.

Do crinoids have hearts?

Crinoids do not have hearts, they use the water vascular system for circulation. This system is also used as excretory and respiratory systems.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! For more relatable content, check out these starfish facts and crown-of-thorns starfish facts pages.

You can even occupy yourself at home by coloring in one of our free printable starfish coloring pages.

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