1
Q
Echinoderms
A
only around 7,000 echinoderms
- found in the sea (not on land or freshwater)
5 classes
2
Q
Crinoidea: Class of Echinoderm
A
they are sea lilies and feather stars
- look more like plants than animals
- they have their mouth facing upward
- they have long branches arms that have tube feet
3
Q
Holothuroidea: Class of Echinoderms
A
sea cucumbers - look like the fruit
4
Q
Echinoidea: Class of Echinoderms
A
sea urchins and sand dollars
- their body is like a disk or globe shape
- their skeletal plates are fused into a rigid skeleton called a test
5
Q
Ophiuroidea: Class of Echinoderms
A
brittle stars and basket stars
6
Q
Asteroidea: Class of Echinoderm
A
sea stars
- their body has 5 or more arms (shaped like a star)
- arms are thick and not distinct from central body disk
- the tube feet are in open grooves
7
Q
Deutorostomes
A
echinoderms are deutorostomes
- they have a type of radial symmetry but are still in the clade bilateria
- they adpated radial symmetry
8
Q
Success of Echinoderms
A
radial symmetry with triploblat, a ceolom and an endoskeleton make them successful
type of radial symmetry = pentradial symmetry (body symmetry using 5 parts that are arranged around a central axis)
9
Q
Water Vascular System
A
they have a water vascular system (WVS)
- system filled of fluid canals that only echinorderms have
- WVS is derived from the coelom
- WVS help with movement, gas exchange, circulation, and feeding
10
Q
Process of Water Vascular System of Sea Star
A
the WVS is a hydraulic system
1. water enters the WVS thru the madreporite and then into the stone canal
- then it travels down to and around the ring canal
- then it flow out to each arm thru the radial canals
- from the radial canal, the water flows into the tube feet
11
Q
Tube Foot - Water
A
water is held and reserved in the relaxed ampulla
- when muscles of the ampulla contract, the pressure is put on the water in it
- water is non-compressible, so it gets pushed into the podium of the tube foot (this extends the podium of the tube foot) – the tip
12
Q
Support and Movement
A
the endoskeleton provides support
- made of calcium carbonate plates = ossicles
- the plates join with each other in diff ways — degree of joint movement varies
- spines project on the surface
- they are covered in thin protective layer of skin
13
Q
Spines
A
the endoskeleton extends past the epidermis as spines
- the sea starts have show spines, but the urchins have long spines
*some have no spines
*spines look diff
14
Q
Skeleton
A
in some species, like the sea urchin, the plates of skeleton are locked together to form rigid structure
- most sea stars can flex their arms showing that their skeleton has gaps and flexible plate junctures
- sea cucumbers have small ossicles
- they have scattered skin
- most echinoderms use the tube feet of the WVS to move along the surface
15
Q
Pedicellaria
A
sea urchins and sea stars have small claw-like structures called pedicellaria on their surface
- they can function to keep the surface clean, protect from predators, and capture prey
16
Q
Mutable Connective Tissue
A
the ossicles are bound together with connective tissue
- it can alter the degree of stiffness and fluidity – changes from rock hard to liquid in second
- sea cucumbers with very small ossicles have mutable connective tissue in their entire body wall so they make the most dramatic changes
17
Q
Feeding Strategy and Digestion
A
they have filter feeders, grazers, carnivores
- have complete digestive tract
18
Q
Gas Exchange and Circulation
A
they exchange gas in sea stars across skin gills, which are extensions of the coelom
- pushed out to the surface between the spines
- oxygen moves from water into environment into the ceolomic fluid of the skin gill and CO2 moves into the opposite directions
- gas exchange happens across the surface of the fluid-filled tube feet
*digested nutrients from the digestive tract are circulated along with O2 around the body by the coleom
19
Q
Excretion of wastes
A
they don’t have any excretory organs
- nitrogenous waste diffuses across the skin gills from the coelomic fluid and across the tube feet
- the salt concentration of the sea star’s body is equal to the salt in the water
*no net movement of water
20
Q
Can’t live in freshwater
A
they can’t live in freshwater because the salt concentration would be higher inside the echinoderm than outside
- water would diffuse inside, which would case the echinoderm to malfunction bc the solution concentrations wouldn’t be normal in the cells
*because they don’t have an excretory organ, they can’t live in freshwater
21
Q
Nervous System and Sensory Organs
A
they don’t have a brain
sea star: nerve ring around the mouth with radial nerves extending to diff parts of the body
- no centralization of neurons that integrate sensory info and send out response so no head
*they have sensory cells that detect dissolved chemicals, water current, light, gravity, and touch
22
Q
Reproduction
A
sexes are separate
- fertilization is external
- echinoderms can regenerate lost parts like arms in the sea star
23
Q
Arm of Sea Star
A
each arm of sea star has short sensory tentacles at the end that respond to chemical and vibrations in the water
- they also have a red eye that is sensitive to light and can see very little detail
*sea star often lifts the end of the arm to percieve light and movement
24
Q
Protostomes vs. Deuterostomes
A
protosotomes: the mouth is formed first from the blastopore
deuterostomes: the anus is formed first from the blastopore
- phylum Chordata and Echinodermata are dueterostomes
25
Echinorderms are Deuterostomes
their blastapore develops into the anus
26
Pentraradial Symmetry
the ancestors of echinoderms are motile, bilaterally symmetrical
- water vascular system evolved -- used for suspension feeding and gas exchange
- water vascular system new function = locomotion (free-moving)
27
Symmetry for the diff types of echinoderms
Brittle Star Larva: ciliated, free swimming, bilaterally symmetrical larva
- the larva eventually goes to adult form
- adult = pentraradial symmetry
Sea star:
- larva = bilateral
- adlt = pentraradial
urchin:
- bilateral larva
***echinoderm adults have pentraradial symmetry but also are triploblastic, have a ceolom and endoskeleton
28
Sea Star Characteristsics (part of Asteroidea group)
- bilateral larva
- water vasclar system
- calcium carbonate endoskeleton
- mutable connective tisse
- pentradial symmetry
- no excretory organ
29
Sea Star Dissection
underside = oral surface
side facing up = aboral surface
the arms are not well-definied from the central disk of the body
30
Sea Star Aboral Surface
aboral = side facing up
- has spines = extensions of the endoskeleton
- spines are made of calcium carbonate
skin gills: soft bumps between the spines
- they are extensions of the ceolom
- gas exchange between the surrounding water and the ceolomic fluid happens across the skin gills
- the ceolom circulates oxygen to all parts of sea star
pedicellaria = they remove debris, small organisms, and larvae that may settle on their surface
31
Pedicalleria
they are tiny pinches are on stalks
- urchins and sea stars
defense against predators
- pinches attacking sea star
- they keep the surface clean
ex: they removes barnacle larvae sitting on the surface
32
Aboral Surface of Sea Star - External Anatomy
on the periphery of aboral surface of the central disk, they have a madreporites = button shaped
- the madreporite is the opening into the water vascular system and acts like a strainer to keep debris out of the system
33
Tube feet in Sea Star
groove is on the bottom side of the arm
- each tube foot is fluid filled muscular tube
- the inner end is a bulbous structure =ampulla
- the outer end has a sucker in sea stars = podium
- the podia pass thry the body wall and extend into the groove
34
Tube Feet
they help move, attach to the substrate and to prey
- they form a respitory exchange surface (skin gills do this too)
- excretion of nitrogenous waste also happens across their surface
35
Sea Star - Oral Surface
the mouth is in the middle (center between all of the five legs)
- there are grooves along each arm with tube feet projecting into the groove
- each arm has a groove = abulacral groove that runs along the middle
36
Ossicles in Sea Star
they are joined together for sea stars that is flexible
- this allows the sea star to move its arms in all directions
- the ossicles in skeleton = endoskeleton
37
Calcium Carbonate Endoskeleton
the ossciles are connected by collagenous tissue and muscles
- the skeletons have differences in stiffness (this is from the connective tissue)
38
Digestive System of Sea Star
sea stars have 2 stomachs
cardiac stomach: folded and big
- extends out of the body to digest prey
after this, food passes up into the pyloric stomach = flat and smaller
digestion happens in the digestive glands = digestive ceca
- nutrients get absorbed from the ceca into the coelom and then distributed
- undigested material passes out of the body on the aboral surface thru the anus, which is attacthed to the pyloric stomach
39
Reproductive System of Sea Star
the reproductive structures of sea star are underneath the pyloric cecae
- sea star gonas look like mini grapes
- they get enlarged during breeding season
*they have separate sexes -- fertilization is external
- sea stars release their gametes into the sea where the sperm and egg meet
40
Decentralized Nervous System in Sea Star
there is a nerve ring around the central disk
- radial nerves extend from the nerve ring down each arm
- each arm of sea star has sensory tube feet at the tips that sense vibrations in the water, olfaction, and eye spots on each arm
41
Water Vascular System Process
water enters thru the madreporite
- the system of canals is derived from the coelom
1. water enters thru the madreporite
2. it travels down the stone canal and into the ring canal which encircles the central disc
3. water flows into each arm by the radial canal
4. water flows from the radial canal into the ampulla and tube feet
***water vascular system helps with movement, gas exchange, circulation, excretion of nitrogenous waste, and feeding
***water vascular system is part of the coelomic space
42
How Tube Feet Move
the muscles of the ampulla contract which pushes water into the tube foot
- then the nervous system control direction of movement
43
Excretory System Functions
gets rid of the nitrogenous waste
- also does osmoregulation: maintains a stable internal balance of water and solute concentrations, regardless of external conditions
44
Echinoderms don't have excretory organs - instead
they get rid of nitrogenous watse by: the nitrogenous waste diffuses out of the body across the skin gills and tube feet
regulation of water in body: echinoderms marine only
- the solute concentration in sea star body is the same as concentration in seawater
- water and solute diffuse easily across the surface of the body
45
Mutable Connective Tissue
enchinoderms have special connective tissue with mechanical properties that can be changed quickly and reversibly
- it can change from being stiff to being very soft and then back to stiff
- it's controlled by the nervous system
*collagen in the skin - porteins from the crosslinks between the collagen fibers
*in echinoderms, cross links can be added (makes body very rigid) or they can be removed (makes body softer)
46
Muscular Connective Tissue is Important
they use this capability (removing or adding cross links) in asexual reproduction by softening this tissue and then splitting apart
- sea star asexually reproduces by splitting into 2 parts
- then they regenrate parts of 2 complete sea stars
*a few species can regenerate a whole sea star from only one arm
2. they also can do this for defense -- they can soften this tissue to let an arm or part of their body be removed by a predator, then they escape, and then regenerate it
47
Musclular Connective Tissue - Energy
they need this for energy sparing maintencnace of posture --- echinoderms are able to maintain postures for long time by locking collagen fibers in place
--- by being stiff, they can maintain it with little energy expenditure
- sea stars can open mussel shells without a lot of energy
- sea urchins have this tissue and can move into rocks and then make their muscle tissue stiff which makes them almost impossible to move from their position
- some brittle stars are suspension feeders -- they can hold their arms up and trap food and maintain this position from the muscle connective tissue `
48
Brittle Stars - comparisons to sea stars
the arms of brittle star are sharply set off from the central disk (sea star they are broadly connected to central disk)
- the sea star uses tube feet, part of the waster vascular system to move
- the brittle star uses flexible arms to pull the body in a rowing motion
49
Brittle Stars Flexibility
they have vertebral ossicles - plates that are joined like vertebrae to make them flexible
50
Brittle stars arms and feet
their arms don't have internal organs like those for digestion or reproduction
- the arms have spines and tube feet that don't have suckers
- the tube feet are mostly used for feeding and sensory perception
- brittle stars can detach and arm and get away if there's danger (can regenerate arms)
51
Brittle Stars and Coral
they have a mutually beneficial relationship with coral
- they clean and remove harmufl things
- the brittle stars are suspension feeders
- the coral gives them a structure to feed on
- the brittle star shifts so it prevents larvae and things from living on the coral's tissue which helps it feed easier
- some brittle stars are predators - some are scavengers and eat dead organic matter
52
Sea Urchins - Endoskeleton
their endoskeleton = test
- the skeleton is made of tightly fused plates of ossicles that encircle the sea urchin
- there are plates with holes and those with no holes
- the tube feet pass thru the holes
- sea urchins have long spines
- the spines form a ball and socket join on the test
- the joint allows the spines to move
53
Pedicellaria - Sea Urchins
they are more prominent in urchins than in sea stars
- they are on stalks, have jaws that open and close
- they are used to keep the surface clean, for defense, and grab food
- the pedicellaria of some species of sea urchins have toxic susbtances
54
Tube feet in Sea Urchins
the tube feet can extend past the spines
- they are used for locomotion, to grab food, hold onto surfaces, gas exchange and sensing
- suckers at the end of tube feet
55
Feeding Structure of Urchins
they have a complex system of ossicles and muscles = aristotle's lattern
- it surrounds the mouth
- has 5 teeth
- urchins use this sturcture to scrape food (usually alagae) from surface or tear off pieces of food like kelp and seaweed
56
Kelp Forest, Urchins and Bacteria Story
Kelp forests: they help make habitat
- support so many species
- shoreline protetction and do carbon sequestation
sunflower sea star: they are a predator in the kelp forest
- they help maintain the balance by eating sea urchins
sea urchins:
- they graze
- in a healthy enviornment, they eat kelp -- but now, there's an issue
57
Sea Star Wasting Disease
5 billion sunflower stars wasted away
- because of the sunflower stars dying out, the urchin population grew so much which meant they ate so much of the kelp forest
= Urchin Barren
58
Bacteria that causes the Sea Star Wasting Disease
they collected animals from the field
- if they became sick, they put them near healthy sea stars to see if they became sick too
- the newly infected stars --- they took their ceolomic fluid and inserted it into healthy stars
59
Sea Cucumbers (Holothuroidea class of echinoderms) Endoskeleton
their skeleton is reduced to miscroscopic ossicles that are embedded in the body wall
- they don't articulate with each other
- the sea cucumber has a leathery feel to it
*they have dermal osscicles
- connective tissue of dermal layer
60
Sea Cucumber Symmtery
they have bilateral symmtery and tube feet
- they are elongated on the oral-aboral axis
- being elongated causes them to lie on their sides
- the mouth is at one end and the anus at the other
- ventral side facing = ventral side facing the substrate
61
Ventral and Dorsal sides of Sea Cucumber
tube feet are diff on the dorsal and ventral sides
dorsal side: 2 less distinctive rows
ventral side: 3 more distinctiive rows of openings for tube feet
- the tube feet on the ventral side are bigger for movement
- sea cucumbers that move in one direction across the substrate with ventral side down are similar to animals with bilateral symmetry
*ventral tube feet have suckers
62
Sea Pig
they are kind of sea cucumber
- they have anterior end -- (they aren't cephalized) with a mouth and a posterior end with anus and move directionally with oral end
63
Feeding Strategy of Sea Cucumber
they are deposit feeders --- they move along the bottom of the ocean using the oral tentacles to feed
- some are suspension feeders
64
Extensive Mutable Collagenous Tissue
the sea cucumbers endoskeleton is made of microspic ossicles that don't articulate
- their body wall, has a lot of mutuble collagenous tisse
- they can be stiff or liquified
65
Defense Adaptations - Sea Cucumbers
when sea cucumbers are distrubed, like when they're attacked by a predator, they eject long white tubules from their anus
- once put into the water, the tubules get longers and become sticky when they touch something
- the tubules are very good at entangling and immobilizing potential predators -- the white tubules ejected by some sea cucumbers can be toxic
66
Evisceration
*sea cucumbers do this
- this is when they expel their internal organs = defense strategy
- the internal organs get expelled from the body -- this is suppossed to scare predators
- they also might evicerate to flush out parasites or it might happen when O2 levels are too low in water
- the organs regenerate - the digestive tract gets regenerated first
67
Crinoids - Sea Lillies and Feather Stars - Body Plan
the main part of the body supported by stalk in sea lillies and by grapsing claws called cirri in feather stars
- sea lilies are permanently attached to susbtrate - feather stars swim using arms and can perch to rest using cirri
- they always have the oral side facing up and the ring of arms about the mouth gives them a flower like appearance
- the stalk and arms are made of jointed ossicles which gives them flexibility -- they don't have stalk
- crinoids have 5 arms or more that extend from the body
- the arms then branch and in some crinoids the branches also brancg
68
Feeding Strategy of Crinoids
they're suspension feeders -- the tube feet are fully extended and held erect from branches forming a food-trapping mesh
- the tube feet secrete mucus, trap food which is flicked into the groove -- then the food is transported to mouth by cillia in the groove
Bio 102 - LAB
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