Jenis Crinoid Feather Stars
Jenis Crinoid Feather Stars
Jenis Crinoid Feather Stars
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<strong>Crinoid</strong><br />
<strong>Feather</strong> <strong>Stars</strong><br />
Scientific (Genus Species) & Common Names<br />
Phylum: Echinodermata<br />
Subphylum: Crinozoa<br />
Class: <strong>Crinoid</strong>ea<br />
http://www.youtube.com/watch?v=jOAbKWNQu20<br />
General Facts
• <strong>Crinoid</strong>ea comes from the Greek word krinon (a lily) and eidos (form)<br />
• Other Names: Sea lilies, feather starts.<br />
o Sea lilies refer to the crinoids in their adult forms, which are attached to<br />
the sea bottom by their stalks and resembling lilies. <strong>Feather</strong> stars refer to<br />
their unstalked forms.<br />
• There are two groups of living crinoids:<br />
o Those with columns, the living stalked crinoids.<br />
o Those without columns, the comatulids.<br />
• They come in an array of colors and the size of their living forms are few inches<br />
to a couple of feet in dimension<br />
o However, some extinct crinoids were great in size. One had a stalk of<br />
nearly 21.5 meters. length.<br />
• Their average lifespan is 15 years.<br />
• Their fossils have been used for jewelry. For example, Fossilised crinoid<br />
columnals extracted from limestone quarried on Lindisfarne (UK) or found<br />
washed up along the foreshore were threaded into necklaces or rosaries and<br />
became known as St. Cuthbert's beads.
Evolutionary Relationships<br />
Fossil <strong>Crinoid</strong><br />
• <strong>Crinoid</strong>s are the least understood of the living echinoderms, and their skeletal<br />
remains are one of the most abundant and important of fossils.<br />
• There are two competing hypotheses pertaining to the origin of the group:<br />
o The traditional viewpoint holds that crinoids evolved from within the<br />
blastozoans (the eocrinoids and their derived descendants the cystoids)<br />
where the most poplar alternative suggests that the crinoids split early<br />
from among edrioasteroid.<br />
o This debate is hard to settle because they all share many characteristics<br />
including radial symmetry, calcareous plates, and stalks or direct<br />
attachment to the substrate.<br />
• The earliest known group of crinoids date to the Ordovician period (roughly 490<br />
million years ago) and underwent two major adaptive radiations during the<br />
Paleozoic Era (245-570 million years ago).
• They are the most common fossils from Paleozoic-age marine rocks and were<br />
most diverse at this time because they were able to live in shallow water where<br />
plankton was abundant.<br />
• They were able to live in the shallow water where the predators could see them<br />
because Paleozoic predators were less efficient than modern predators.<br />
• Many different kinds of stalked crinoids were able to evolve by specializing on the<br />
kinds and sizes of plankton that they ate because plankton is variable in size and<br />
has a large range of different types of algae and microscopic animals.<br />
• They were major carbonate producing organisms during the Paleozoic and<br />
Mesozoic Eras with entire carbonate shelves composed mostly by crinoidal.<br />
Carboniferous crinoid<br />
• The geological history of the crinoids demonstrates how well the echinoderms<br />
have adapted to filter feeding and the fossils of other stalked filter-feeding<br />
echinoderms, such as blastoids, are also found in the rocks of the Palaeozoic<br />
era.<br />
o <strong>Crinoid</strong>s evolved a plant-like morphology so that they could remain<br />
attached to the seafloor while they spread their arms to catch food.
o Their Pinnules arose in several lineages during the Paleozoic and are<br />
characteristic of all post-Palaeozoic crinoids.<br />
o The comatulids evolved from stalked crinoids by losing their column during<br />
their larval development.<br />
• <strong>Crinoid</strong>s came close to extinction towards the end of the Permian Period, about<br />
250 million years ago.<br />
• The end of the Permian was marked by the largest extinction event in the history<br />
of life and fossil records show that nearly all the crinoid species died out at this<br />
time.<br />
• The one or two surviving lineages eventually gave rise to the crinoids populating<br />
the oceans today.<br />
• The close relatives are starfishes, sea urchins, sea cucumbers, and brittle stars<br />
which reside in the same phylum.<br />
• These species are related to eachother because they share many similar<br />
features.<br />
o For the most part, their body parts are arranged around a central axis.<br />
o They have rough, spiny surfaces which is what their phylum means (“spiny<br />
skin”).<br />
o They have a special kind of radial symmetry based on multiples of five.<br />
o They share a unique body system called the water-vascular system, which<br />
no other group of animals possess.
Physical Traits<br />
Living <strong>Crinoid</strong><br />
• They are attached suspension-feeding echinoderms with a cuplike body<br />
supported upward by a stalk or claws (cirri).<br />
• They have a mouth on the top surface facing up surrounded by usually 5<br />
featherlike feeding arms.<br />
• All echinoderms have pentameral symmetry (organization in patterns of 5) and<br />
crinoids can have as few as 5 arms, but usually have arms in multiples of 5.<br />
• They have a u-shaped gut and their anus is located next to the mouth. They also<br />
have sticky mucus covered tube-like feet.<br />
• Most of their body consists of an endoskeleton composed of many calcareous<br />
(composed of calcium carbonate) pieces embedded in their skin called plates or<br />
ossicles.<br />
• The crinoid is encased in the aboral cup, which is typically composed of 2-3<br />
circles of plates.<br />
• Five radial plates (the uppermost circlet of aboral cup plates) are aligned with the<br />
radial water vascular canals and give rise to five arms on the oral side of the<br />
body.
o So each arm is a series of ossicles extending outward from the body.<br />
• The arms contain extensions of coelomic (body cavity), nervous, water vascular,<br />
and reproductive systems<br />
• They also have an ambulacra (radial area) groove bordered by fingerlike tube<br />
feet, or podia, which are extensions of the water vascular system as well. They<br />
are also used in suspension feeding and respiration<br />
• All living crinoids are pinnulate, bearing a small side branch, pinnule, on<br />
alternating sides of successive ossicles along the arm. These pinnules bear the<br />
food-gathering tube feet.<br />
o Pinnules arose in several lineages during the Paleozoic and are<br />
characteristic of all post-Palaeozoic crinoids.<br />
• <strong>Crinoid</strong>s have muscles, nerves, a gut, a reproductive system and other features<br />
Feeding<br />
of advanced animals.<br />
• They are all passive suspension and filter feeders and because they produce no<br />
feeding or respiratory current, they rely more on the water movement around<br />
them, feeding by filtering small particles of food from those seawater currents.<br />
• Their diet consists of a variety of protists (i.e. diatoms and other unicellular algae,<br />
foraminiferans, actinopods), invertebrate larvae, small crustaceans, and detrital<br />
particles.<br />
• To feed they use their featherlike arms that radiates from the central body which<br />
each bears an open ambulacra groove bordered by triads od fingerlike podia
(tube feet) which as mentioned before, are terminal extensions of the water<br />
vascular system.<br />
• This is a complex system of muscles, canals, pouches, bladders, tubes, and<br />
suckers connecting to numerous tube feet that allow Echinoderms to use this<br />
hydraulic system for locomotion, food, waste transportation, and respiration.<br />
• They are also typically nocturnal and will come out after dark to perch upon a<br />
coral or other structure.<br />
• Then they spread out their arms perpendicular to the current to feed, turning their<br />
“plumage” into the current to feed while being restricted to one spot.<br />
• They then their arms and feet to trap their food and flicking/filtering it into their<br />
mouths.<br />
• After a food particle is captured, the shortest tube foot wraps it in mucous<br />
secretions where ciliary tracts on the groove floor then transport it toward the<br />
mouth and ingested.<br />
o The mouth descends into a short esophagus and because there is no true<br />
stomach, it connects directly to the intestine, which runs in a single loop<br />
right around the inside of the calyx.<br />
o The intestine often includes numerous diverticulae (outpouching of a<br />
hollow or a fluid-filled structure in the body), some of which may be long or<br />
branched.<br />
o The end of the intestine opens into a short muscular rectum, which<br />
ascends towards the anus. Waste is collected by phagocytic (white cell)<br />
coelomocytes (immune cells of lower coelomate animals).<br />
• Oxygen is absorbed primarily through the tube feet, which are the most thin-<br />
walled parts of the body, using the water vascular system.<br />
http://www.youtube.com/watch?v=8uZJVSFwixY
Locomotion<br />
• Most crinoids are free-swimming and lack a stem, however stalked crinoids can<br />
move and can reach speeds much higher than 0.6 meters (2ft) /hr<br />
• As previously mentioned, echinoderms utilize the water vascular system to<br />
accomplish a lot of things essential for survival, one of them being locomotion.<br />
• Echinoderms move by utilizing their canals of tube feet and alternately<br />
contracting muscles that force water into the tube feet, causing them to extend<br />
and push against the ground, and then relaxing to allow the feet to retract.<br />
• Echinoderms can use their tube feet or similar extensions of the water-vascular<br />
system to also capture planktonic foods or burrow through substrates.<br />
• On the underside of the calyx, free-living varieties have a ring of specialized short<br />
arms called cirri (claws) that are used for crawling around and for holding on to<br />
surfaces.<br />
• However, they can also actively swim about by rhythmically waving their arms.<br />
http://www.youtube.com/watch?v=MoETr8BNWLQ<br />
http://www.youtube.com/watch?v=cZcomBnNKXg
Avoiding being eaten<br />
• Stalked crinoids today live only in the deep ocean, in quiet water below the<br />
lighted zone where it’s too dark for predators so seem them.<br />
• They live so deep in the water because they are attached to the sea floor and<br />
can’t escape, making them very vulnerable to predators in lighted shallow water.<br />
• They can crawl around on a reef, hiding in crevices during the day and climbing<br />
onto corals at night to feed<br />
• By only feeding at night, they make it harder for predators to find them.
Reproduction and life cycle<br />
• They are dioecious, meaning they separate genders and genitalia.<br />
• They have no true gonads and reproduce by producing their gametes from<br />
genital canals found inside some of the pinnules.<br />
• The pinnules then rupture after some time to release the sperm and eggs into the<br />
water around them.
• The fertilized eggs then hatch to release free-swimming vitellaria larva.<br />
o This larva has rings of cilia running around the body with a tuft of sensory<br />
hairs at the upper pole.<br />
o There have been some cases where the female crinoid has been known<br />
to temporarily brood the larvae using chambers in their arms.<br />
• The larva doesn’t feed and lasts only for a few days before it settles at the bottom<br />
and attaches itself to the underlying surface using a adhesive gland on its ventral<br />
surface.<br />
• The larva then metamorphoses into a stalked adult.<br />
o Free-swimming feather stars sometimes go through this stage too, with<br />
the final stage ending with the adult breaking away from the stalk.<br />
• Within 10-16 months, they are able to produce after becoming adults.<br />
Ecosystem<br />
• They are chiefly deep-sea organisms, mostly inhabiting deep water, usually<br />
attached to sediment resting at the bottom of a stream.<br />
• They relatively live in environments with plankton
• Thy approximate 80 surviving species of stalked crinoids are restricted to depths<br />
greater than 200 m, with the shallowest occurring in 100 m.<br />
• About 65% of living comatulids occur at shelf depths (