Echinodermata PDF

1 OUTLINE Phylum Echinodermata 1. Introduction 2. Body Forms 3. Water-Vascular System 4. Pedicellariae 5. Respiration 10 INTRODUCTION Echinoderm featu...

1 OUTLINE Phylum Echinodermata 1. Introduction 2. Body Forms 3. Water-Vascular System 4. Pedicellariae 5. Respiration 10 INTRODUCTION Echinoderm features that are found in no other phylum 1. Secondary radial symmetry 2. A water-vascular system 3. Pedicellariae – i.e. minute pincer-like structures on the outer surface of many members of this phylum 4. Dermal Branchiae (papulae) – i.e. projections of the coelomic cavity with respiratory (and excretory) functions 5. An endoskeleton of plates or ossicles (sometimes spiny) 11 INTRODUCTION Echinoderm features that are found in no other phylum Cross section pedicellariae dermal branchiae perivisceral ossicles coelom tube feet (of water vascular system) 12 BODY FORMS - cephalization absent; no anterior or posterior ends - body surfaces designated oral (bearing mouth) or aboral No cephalization!! Asteroidea oral surface aboral surface formed by many tooths 13 BODY FORMS Ophiuroidea Arm Madreporite Mouth (Anus) - Ambulacral groove absent. - Pedicellariae absent. - Tube feet present (WVS). - Papulae absent. 14 BODY FORMS brittlestar seastar Asteroidea Ophiuroidea Perivisceral Ceolom Radial Canal Tube Foot more sophisticatted Radial nerve Hyponeural and Ectoneural controls relaxation of muscle nerves contracting and relaxing muscles 15 BODY FORMS Brittlestar is armoured Asteroidea Ophiuroidea Aboral Shield Muscle more muscles muscles with spines andspikes arm Lateral Shield Oral Shield with Spines covers up Ambulacral Ossicle Vertebra 16 BODY FORMS Asteroidea Ophiuroidea Locomotion - Arms bend and move in all - Tube Feet. tube feets for locomotions directions. arms for locomotions - Most agile Echinoderms. 17 BODY FORMS Echinoidea and Holothuroidea Expansion of Oral Surface (Ambulacral surface) Asteroidea Echinoidea urchin mouth seastar oral surface 18 BODY FORMS Echinoidea and Holothuroidea Expansion of Oral surface (Ambulacral surface) Echinoidea Holothuroidea sea urchin sea cucumber 19 BODY FORMS Echinoidea (Sea Urchin) - compact body enclosed in an endoskeletal test (ossicles that are close fitting plates) test architecture: - 10 double rows of plates with movable spines one bigger one smaller 4 3 2 5 1 6 10 7 9 8 20 BODY FORMS Echinoidea test architecture: - 5 pairs of plates form ambulacral rows with rows of pores for tube feet 1 5 2 tube feet 4 3 location analogous to ambulacral groove  there are 21 BODY FORMS muscles at the beginning of spines Echinoidea circles = spines coming out Interambulacral area Interambulacral area Ambulacral Row Ambulacral Row circles are pores, opening, tube foot come out 22 BODY FORMS Echinoidea opening to the water vascular systtem Aboral pole Madreporite (Rounded) anus Anus water vascular system digestive system tooth feet Mouth Oral pole (Flattened) Aristotle’s Lantern feeding apparatus, mouth complete digestive system 23 BODY FORMS Echinoidea can extend, for locomotion Tube Foot (podia) Primary Spine (can contain toxins) longer this is why it hurts Secondary Spine shorter, non poisonous Pedicellariae (can be very poisonous) again is poisonous 24 BODY FORMS Holothuroidea (Sea cucumber) - body elongated in the - soft bodied with “leathery” oral-aboral axis body wall. oral 'surface' aboral 'surface' tentacles - ossicles: tiny and embedded for feeding within body wall. oral tube feet (oral podia) microscope ossicles 25 BODY FORMS Holothuroidea - ambulacral regions with tube feet often restricted to ventral surface (sole) ventral dorsal Divium (Sole) Trivium functional tube feets for locomotions reduced tube feet of dorsal tube feet of ventral ambulacra (Divium) ambulacra (Trivium) like appendix, no purpose, locomotion coz it does not claw anymore 26 WATER-VASCULAR SYSTEM - unifying characteristic of phylum Echinodermata - fluid-filled canals leading to tube feet - functions include; - locomotion (primary function) - predation eat - contributes to gas exchange & excretion oral surface, the teeth is under bivalve 27 WATER-VASCULAR SYSTEM single opening to water Ring canal Madreporite vascular system - sieve plate linking the water-vascular system to the outside plate to preventt debris from entering Stone canal - reinforced canal (calcium carbonate plates) connecting madreporite to ring canal transport system seawater into water vascular Polian vesicles Tube foot - accessory (storage) fluid structures Ampulla helps tube feet to function Lateral canal tube foot can extend!! Radial canal - perpendicular branching of the radial canal leading to the tube foot - radiate symmetrically from ring canal and run the length of the “arm” WVS shown is typical of Asteroidea 28 WATER-VASCULAR SYSTEM Ampulla and Tube Foot (podium) ampulla - circumlongitudinal (CLD) ampullary ampulla muscles line inside of ampulla inside the body muscles body lateral canal - connected to tube foot via a one-way valve ossicles water can enter the ampulla and podium but they cant go back podium can be extended and retracted water - contains longitudinal (LD) retractor muscles - circular muscles not present hydrostatic pressure 29 WATER-VASCULAR SYSTEM Tube foot extension - circumlongitudinal muscles contract and podial longitudinal muscles relax - fluid forced into podial region extending it by hydraulic pressure - end of podium gains traction by suction or duo-adhesive glands CLD muscle LD muscle 30 WATER-VASCULAR SYSTEM Tube foot retraction extension - podial circumlongitudinal longitudinal muscles contract and circumlongitudinal podial longitudinal muscles relax - fluid forced into ampullary region, podial region inflating extending it byit hydraulic by hydraulic pressure pressure -- end in both cases, one-way of podium valve between gains traction lateral by suction canal and foot or duo-adhesive prevents glands loss of hydrostatic pressure CLD muscle LD muscle shoter circumlongitidunal, longer longitidunal 11 INTRODUCTION Echinoderm features that are found in no other phylum pedicellariae dermal branchiae perivisceral ossicles coelom tube feet (of water vascular system) 31 PEDICELLARIAE - consist of 2 – 3 calcium carbonate ossicles (valves) create a valve - supported by an immobile basal ossicle - ends can be moved apart and together by small muscles Functions: - removal of unwanted organisms and debris valve - protect dermal branchiae - capture of live prey closer muscles opener muscle basal ossicle Spine with rosette 32 PEDICELLARIAE - in sea urchins pedicellariae are often stalked - can also contain venom - pedicellariae may also be used to grasp and hold objects for camouflage epithelium produces secretes toxin 33 GAS EXCHANGE Asteroidea - occurs across dermal branchiae (papulae) - dermal branchiae are projections of the coelomic cavity covered with epidermis and lined with peritoneum dermal branchiae gas exchange 34 GAS EXCHANGE Asteroidea - ciliary action moves fluids in opposite direction (countercurrent) extention of the cillium epidermis Water has cilia for gas exchange there is counter current exchange systttem peritoneum draws water from left to right coelomic fluid ossicles from right to left coelomic fluid ocean water more oxygenated coelomic fluid deoxygenated there is a gradient 35 GAS EXCHANGE Holothuroidea Respiratory Tree mouth modified tube feet - chief gas exchange organ of holothuroids - branching diverticulum of the cloaca (or rectum) diverticulum (extenion) of the gut gastrointestinal 1. cloacal muscles tract contract (cloacal dilation) lateral tube feet 2. water enters through anus right side 3. anal sphincter closes & is complete cloaca contracts (water Respiratory Tree forced into tree) 4. one long exhalation (contraction of the tree with anal sphincter open ) to empty no dermal branchiae, no pedicellariae Anus Cloacal Muscles 36 GAS EXCHANGE Holothuroidea and Pearlfish -spends days in the respiratory tree of sea cucumbers. - enters when sea cucumber “inhales”. - exits when sea cucumber “exhales” (at night, searches for food). Sea Cucumber