La dissection étoile de mer
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0:03 - 0:04University of Lille 1 - Faculty of biology
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0:05 - 0:06Animal Biology
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0:34 - 0:38Sea star dissection
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0:40 - 0:42Morphology
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0:46 - 0:49The Asteria rubens sea star
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0:49 - 0:51is an Echinoderm
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0:51 - 0:53belonging to the class of Asteroidea.
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0:55 - 0:56It lives on costs
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0:56 - 0:58we may find it in the intertidal zone
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0:58 - 1:00at low tide.
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1:02 - 1:04It feeds chiefly on mussels
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1:04 - 1:06fixed on rocks.
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1:09 - 1:12The sea star is part of the foreshore food web
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1:12 - 1:15and can fall prey to other animals.
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1:21 - 1:23The body of the sea star is flattened,
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1:23 - 1:26in a shape of a star with 5 arms.
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1:27 - 1:30The arms merge at their base
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1:30 - 1:32and are attached to the flat disk.
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1:38 - 1:40The arms are called radius
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1:41 - 1:45The zones between the arms are called interradius.
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1:48 - 1:52This organisation is representative of the pentaradial symmetry,
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1:52 - 1:56characteristic of the adult echinoderms.
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1:59 - 2:01The sea star has two faces:
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2:02 - 2:03the upper face,
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2:03 - 2:05or aboral surface,
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2:05 - 2:08is convex and pigmented.
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2:08 - 2:10The bottom side
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2:10 - 2:11or oral surface,
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2:11 - 2:13is flattened, and clearer,
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2:13 - 2:15in contact with the substrate.
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2:18 - 2:20This surface includes the mouth,
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2:20 - 2:22located in the middle of the flat disk.
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2:26 - 2:27On the aboral surface,
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2:27 - 2:29at the interradius level,
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2:29 - 2:32we can see a whitish limestone plate,
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2:32 - 2:34the madreporic plate.
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2:37 - 2:40There are bony spines convering the body,
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2:40 - 2:43organized in rows.
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2:43 - 2:45On the aboral surface,
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2:45 - 2:50there is a row in the middle of each arm
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2:50 - 2:52and two or three lateral rows.
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2:56 - 2:58By turning the sea star over,
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2:58 - 3:01we can see a supramarginal row
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3:02 - 3:05and an inframarginal row
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3:08 - 3:11Two rows of prikly adambulacra
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3:11 - 3:13delimit a central furrow,
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3:13 - 3:15the ambulacral groove,
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3:20 - 3:24Every ambulacral groove has 4 rows of fleshy and movable tubes
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3:24 - 3:27tube feet or podia,
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3:28 - 3:30ended by a sucker.
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3:33 - 3:37At tip of each arms we can see eyespots,
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3:38 - 3:40sensory organs red in coulour
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3:40 - 3:42sensitives to the light.
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3:44 - 3:47Integument
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3:48 - 3:49In the sea star,
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3:49 - 3:51the body and the spines are covered
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3:51 - 3:53by an ciliated epidermis
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3:55 - 3:55The dermis,
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3:55 - 3:57situated beneath the epidermis,
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3:57 - 3:59has calcareous plates,
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3:59 - 4:01or ossicles
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4:01 - 4:03in which the spines are articulated.
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4:05 - 4:07The locations of ossicles
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4:07 - 4:09are visibles on the surface of the animal.
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4:12 - 4:15The integument has specialized structures,
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4:15 - 4:16pedicellariae,
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4:19 - 4:22put in the shape of a crown at the base of the spines.
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4:25 - 4:26In Asteroidae,
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4:26 - 4:28they have a form of a pincer with two jaws.
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4:31 - 4:33Pedicellariae are used
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4:33 - 4:34to clean the integument
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4:34 - 4:36and the defense of the animal
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4:39 - 4:42Organs used for the breathing,
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4:42 - 4:44gills or papules,
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4:44 - 4:46are associated with the integument.
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4:49 - 4:52they are between the ossicles of the skeleton.
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4:55 - 4:57The presence of an epithelium
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4:57 - 5:00ciliated on the inner side of the integument
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5:00 - 5:02enables the circulation of the liquid
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5:02 - 5:04inside the body cavity,
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5:04 - 5:06the coelom.
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5:10 - 5:14Echinoderms have a calcareous internal skeleton,
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5:14 - 5:16formed by ossicles.
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5:21 - 5:24the cross section of the arm enables us
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5:24 - 5:27to observe the organisation of the dermal plates.
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5:38 - 5:40We can see:
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5:40 - 5:42a dorsal ossicle
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5:43 - 5:45two supramarginal plates
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5:46 - 5:50and two inframarginal plates each having spines,
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5:51 - 5:54two adambulacra plates
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5:54 - 5:56and two ambulacral plates.
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6:00 - 6:02Between the ambulacral plates,
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6:02 - 6:06there are pores that allows the passage of the tube feet.
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6:11 - 6:14General anatomy
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6:14 - 6:17To observe the internal organisation of the sea star,
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6:18 - 6:21we have to cut the sea star with scissors.
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6:23 - 6:25Incise the integument
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6:25 - 6:27following the outline
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6:27 - 6:29to separate the upper half
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6:29 - 6:32from the lower half of the animal.
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6:34 - 6:37Identify the madreporic plate
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6:39 - 6:43and avoid it when you incise.
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6:47 - 6:50Lift the integument of the aboral surface
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6:50 - 6:52starting from the end of the arms
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6:54 - 6:57and cut carefully the underlying organs
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7:00 - 7:02ending by the flat disk.
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7:06 - 7:10The rest of the dissection will be done in the water.
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7:13 - 7:16In the coelom we can see gonads
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7:16 - 7:19and a part of the digestive system.
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7:22 - 7:25The digestive system
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7:25 - 7:28The digestive system includes the mouth,
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7:30 - 7:33the stomach divided in two superimposed chambers,
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7:34 - 7:37the pyloric ceca and the rectal ceca.
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7:38 - 7:41It ends by a microscopic anus,
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7:41 - 7:43located in the aboral surface.
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7:45 - 7:47The observation of the digestve system
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7:47 - 7:51will be done using the aboral portion.
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7:52 - 7:54In the central part of the disk,
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7:54 - 7:57we notice two rectal ceca.
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8:01 - 8:05Below we notice the upper chamber of the stomach,
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8:05 - 8:09the pyloric portion with a pentagonal shape.
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8:12 - 8:155 canals start from this chamber
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8:15 - 8:18that extend themselves in the arms of the star.
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8:20 - 8:23Each pyloric canal is connected to two pyloric ceca
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8:23 - 8:26that take up a large part of the arms.
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8:29 - 8:30The pyloric ceca,
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8:30 - 8:34composed by dozens of diverticula on dead end
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8:34 - 8:36play a digestive key role
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8:36 - 8:40and are used to the storage of nutrients.
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8:41 - 8:44To observe the rest of the digestive system
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8:44 - 8:47we have to remove the rectal ceca,
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8:49 - 8:51pyloric ceca
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9:04 - 9:06and the pyloric stomach.
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9:10 - 9:14The ventral chamber or cardiac stomach,
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9:14 - 9:17has a shape of five lobes rose.
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9:20 - 9:21For the ingestion of preys,
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9:21 - 9:25this part of the stomach is everted.
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9:27 - 9:29After the external digestion,
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9:29 - 9:32the stomach gets back to its position
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9:32 - 9:36thanks to the contraction of five pairs of retractor muscles
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9:36 - 9:40put in the ambulacral plates.
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9:41 - 9:44To see the mouth,
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9:44 - 9:47we have to detach the retractor muscles
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9:51 - 9:55and remove the portion of cardiac stomach.
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9:56 - 9:58The mouth,
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9:58 - 10:00located in the middle of the flat disk,
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10:01 - 10:03surrounded by a membrane,
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10:03 - 10:05the peristomium.
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10:08 - 10:10Reproductive system
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10:12 - 10:14In Asteroidea
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10:14 - 10:15the sexes are separated
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10:15 - 10:18but there is not a sexual dimorphism.
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10:20 - 10:23Gonads are located in the coelom.
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10:26 - 10:28To observe the gonads
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10:28 - 10:31we have to remove the pyloric ceca,
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10:33 - 10:35and the upper chamber of the stomach.
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10:39 - 10:40Every gonad,
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10:40 - 10:42with a granular apsect,
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10:42 - 10:44is divided in deux lobes
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10:44 - 10:48that all extend in two adjacent arms.
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10:51 - 10:53The size of gonads is variable,
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10:53 - 10:57it depends on the state of sexual maturation of the animal.
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10:59 - 11:02Females and males produce gametes
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11:02 - 11:06through genital pores located in the interradius
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11:06 - 11:09at the junction with the flat disk.
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11:12 - 11:14The fecondation is extern.
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11:17 - 11:20Aquifer system
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11:21 - 11:24One of the characteristic of Echinoderms
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11:24 - 11:26is the existence of an aquifer system.
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11:27 - 11:31It is involve in the locomotion and the food intake.
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11:33 - 11:36This system have a network of conduits
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11:36 - 11:37filled with a liquid
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11:37 - 11:41whose composition is close to the sea water
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11:42 - 11:47The aquifer system have a madreporic plate,
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11:48 - 11:50the stone canal,
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11:51 - 11:53the ambulacral ring,
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11:54 - 11:56five radial canals,
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11:57 - 12:00and many tube feet or podia.
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12:02 - 12:05To observe the different parts of the aquifer system
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12:05 - 12:07we have to open the sea star
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12:09 - 12:11and remove the digestive
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12:13 - 12:15and reproductive system.
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12:16 - 12:19The madreporic plate, or madreporite,
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12:20 - 12:23is visible on the aboral surface of the animal.
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12:25 - 12:27This calcareous plate is riddle with holes
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12:27 - 12:29"aquifer pores"
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12:30 - 12:33that permit the sea water to enter in the system.
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12:36 - 12:40The madreporite is in connection with the madreporic canal
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12:40 - 12:42or stone canal.
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12:43 - 12:45This canal
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12:45 - 12:48sostained by superimposed calcareous rings,
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12:48 - 12:51go down toward the oral surface of the animal.
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12:53 - 12:55The stone canal
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12:55 - 12:58rejoin the ambulacral ring surrounding the mouth.
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12:59 - 13:00This ring is hidden
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13:00 - 13:02with calcareous plates of the skeleton.
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13:04 - 13:07On the circumference of the ambulacral ring of the star
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13:07 - 13:09in the interradial position,
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13:09 - 13:13we notice 9 vesicles with an immune function:
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13:13 - 13:15Tiedemann bodies.
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13:19 - 13:22From the aquifer ring goes in each arm
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13:22 - 13:25an ambulacral canal or radial canal,
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13:26 - 13:29located between the epidermis and the ambulacral plate.
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13:32 - 13:37From the radial canal goes many lateral canals.
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13:40 - 13:44Those are connected to the tube feet or podia.
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13:48 - 13:52The injection of a dye into ambulacral canal of an arm
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13:52 - 13:54enables us to hightlight
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13:54 - 13:57a large part of the aquifer system.
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14:01 - 14:04Podia have three parts:
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14:05 - 14:08ampulla or bulbous ampulla
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14:10 - 14:13a muscular and elongated foot
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14:14 - 14:16and a sucker at the end.
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14:21 - 14:24The podia go through the skeleton at pores level
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14:24 - 14:27located between the two adjacent ambucral plates.
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14:30 - 14:32To observe those pores
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14:32 - 14:34we have to scratch the polian vesicules
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14:34 - 14:36on a part of the arm.
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14:38 - 14:40The contraction of the polian vesicles
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14:40 - 14:43allows the turgescence of the tube feet
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14:43 - 14:47and the the monitoring of the sucker
for the locomotion of the animal -
14:51 - 14:54The podia within the ambulacral groove
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14:54 - 14:58are protected by rows of movable ambulacral spines
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14:58 - 15:01and by many pedicellariae.
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15:04 - 15:05Radial canals
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15:05 - 15:08end with sensory tentacles
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15:08 - 15:11close to the eyespot.
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15:16 - 15:18Pedagogical design: Pierre-Eric Sautière Jacopo Viziolo
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15:20 - 15:24Technical production: Bernard Mikolajczyk
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15:25 - 15:29Designs: Jacopo Vizioli
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15:29 - 15:34Computer graphics: 3D MEDICUS
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15:39 - 15:42Voice over: Alain Nempont
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15:44 - 15:47Music; Ambient slamming bass jam, Jay Berlinsky
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15:49 - 15:53Gratitude: Sébastien Lefebvre, Michel Priem
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15:54 - 15:58Gratitude: Patrick Flammang, Michel Jangoux
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15:59 - 16:03SEEM; Education Service and Multimedia
- Title:
- La dissection étoile de mer
- Description:
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« La dissection de l 'étoile de mer » fait partie d'une série de films de biologie qui ont pour sujet les plans d'organisation d'animaux représentatifs des principaux groupes de vertébrés et invertébrés. Grâce à des images HD, des animations et des schémas annotés, ce film montre étape par étape, la démarche de dissection de l'animal. Les différents chapitres de l'ouvrage présentent la morphologie, le tégument, l'anatomie générale, les appareils digestif, génital et aquifère de l'étoile de mer.
- Video Language:
- French
- Duration:
- 16:05
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Maxbeaugeois edited English subtitles for La dissection étoile de mer | |
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Maxbeaugeois edited English subtitles for La dissection étoile de mer | |
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Maxbeaugeois edited English subtitles for La dissection étoile de mer | |
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Maxbeaugeois edited English subtitles for La dissection étoile de mer | |
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Maxbeaugeois edited English subtitles for La dissection étoile de mer | |
![]() |
Maxbeaugeois edited English subtitles for La dissection étoile de mer | |
![]() |
Maxbeaugeois edited English subtitles for La dissection étoile de mer | |
![]() |
Maxbeaugeois edited English subtitles for La dissection étoile de mer |