Orders of class Asteroidea

Order1:-Phanerozonia

1)     Arms are provided with two rows of conspicuous marginal plates.

2)     Oral plates are infra-marginal and aboral plates are supra-marginal.

3)     Pedicellariae are alveolar or sessile type.

4)     Pedia or tube feet are arranged in two rows.

5)     Mouth frame is well developed and adambulacral type.

     Order2:- Spinulosa        

1)     Arms are generally without conspicuous marginal types.

2)     They have infra-marginal oral plates and supra- marginal aboral plates.

3)     They have alveolar or sessile type of pedicellariae.

4)     They have tube feet which are arranged in two rows.

5)     They have well developed mouth frame and adambuacral type.

    Order3:- Forcipulata

1)     They have marginal plates which are inconspicuous or absent.

2)     They have aboral skeleton which is mostly reticulate with conspicuous spines.

3)     They have tube feet which are arranged in four rows and provided with suckers.

4)     They have Papulae on both surface.

5)     They have mouth frame of ambulacral type.

Orders of class Echinoidea

   Order1:- Lepidocentroida

1)     Test flexible with overlapping or separated plates.

2)     Ambulacral plates continue up to mouth lip

   Order2:- cidaroidea

1)     Test is rigid and globular.

2)     Two rows of long narrow ambulacral plates and two rows of inter ambulacral plates.

3)     Ambulacral and inter ambulacral  plates continue up to mouth lip.

4)     C

5)     Five bushy Stewart’s organs are present appended to the lantern.

     Order3:- Aulodonta

1)     Test is symmetrical and globular.

2)     Test composed of two rows each in a ambulacral and inter ambulacral plates.

3)     Ambulacral and inter ambulacral plates continue up to mouth lip.

4)     Gills and sphaeridia are present.

5)     Teeth of aristotle’s lantern  are devoid of keel.

     Order4:- camaradonata

1)     Test  is rigid and rarely oval.

2)     Epiphyses of lantern are enlarged and meeting above the pyramids.

3)     Teeth are keeled.

4)     All the four types of pedicellariae are present.

     Order5:- Clypeastroida

1)     Test is flattened , oval or rounded in shape covered with small spines.

2)     Mouth and apical system  are usually central and oral in position.

3)     Aboral ambulacral areas petaloid.

4)     Aristotle’s lantern is present.

5)     Gills are absent

      Order6:- Spatangoida

1)     Test is oval or heart shaped.

2)     Four aboral ambulacral areas petaloid, fifth not petalloid.

3)     Aristotle’s lantern  absent

4)     Gills absent.

Orders of class Asteroidea

Order1:-Phanerozonia

1)     Arms are provided with two rows of conspicuous marginal plates.

2)     Oral plates are infra-marginal and aboral plates are supra-marginal.

3)     Pedicellariae are alveolar or sessile type.

4)     Pedia or tube feet are arranged in two rows.

5)     Mouth frame is well developed and adambulacral type.

     Order2:- Spinulosa

1)  Arms are generally without conspicuous marginal types.

2)   They have infra-marginal oral plates and supra- marginal aboral plates.

3)  They have alveolar or sessile type of pedicellariae.

4)   They have tube feet which are arranged in two rows.

5)   They have well developed mouth frame and adambuacral type.

    Order3:- Forcipulata

1)     They have marginal plates which are inconspicuous or absent.

2)     They have aboral skeleton which is mostly reticulate with conspicuous spines.

3)     They have tube feet which are arranged in four rows and provided with suckers.

4)     They have Papulae on both surface.

5)     They have mouth frame of ambulacral type.

Characteristics of class Asteroidea

1)     They have flat, pentagonal or star shaped  body.

2)     Oral and aboral surfaces are distinct, the oral surface is directed downwards and the aboral surface upwards.

3)     They have  five to fifty long or short rays or arms radiating symmetrically from central disc.

4)     Mouth is centrally placed at the oral surface surrounded by a membranous peristome.

5)     Anus is small and inconspicuous located more or less eccentrically on the aboral surface .

6)     Ambulacra form prominent grooves provided with podia or the feet.

7)     Ambulacra are restricted to oral surface extending from the peristome to the tips of the arms.

8)     Endoskeleton is flexible made of separate ossicles.

9)     Pedicellariae are small, movable spine like always present

   10) They reproduce by papulae.

11) They have separate sex organs with radially arranged gonads.

12) They are commonly called starfish or sea stars.

13)They form brachiolaria larva or bipinnaria.

characteristics of orders of classes Holothuroidea.

order1:- Aspidochirota

        1) They have numerous tube feet or podia.

        2) They have mouth surrounded by 10-30 mostly 20 peltate or  branched tentacles.

        3) They have pharynx without retractor muscles.

        4) They have a pair of well developed respiratory trees.

order2:- Elasipoda

        1) They have many tube feet or podia.

        2) They have mouth present on ventral surface and is surrounded by 10-20 peltate or branched

              tentacles.

        3) They do not have oral retractor.

        4) They do not have respiratory tract.

 order3:-Dendrochirota
        1) They have numerous tube feet or podia.

        2) They have dendritic oral tentacles or branched or branched like tree branches.

        3) They do not have oral retractors.

        4) They have respiratory trees.

order4:- Molpadonia

        1) They do not have tube feet except as anal papillae

        2) They have digitate or finger shaped oral tentacles.

        3) They do not have oral retractors.

        4) They have respiratory trees.

        5) They have posterior region generally tapering into a caudal portion.

Order5:- Apoda

1) They have vermiform shaped body with smooth and warty surface.

2) They do not have tube feet or podia.

3) They have simple, digitate or pinnate 10-20 oral tentacles.

4) Some of them have pharyngeal retractor.

5) They do not have respiratory trees.

      6)  They have greatly reduced water vascular 

          system.

Characteristics of class Holothuroidea.

1) They have bilaterally symmetrical body, elongated in the oral-aboral axis having mouth at or near one end    and anusat or near the other end .

2) They have rough body surface.

3) They have endoskeleton reduced to microscopic spicules or plates embeedded in the body wall.

4) They have mouth surrounded by a set of tentacles attached to water vascular system.

5) Their locomotory organ of them are tube feet or podia.

6) They have long ,coiled alimentary canal with cloaca usually with respiratory trees.

7) They have usually sexes separate and gonad single or paired tufts of tubules.

8) They are commonly called sea cucumbers.

Characteristics of order Articulata

1)     They are extinct and living crinoids.

2)      They have penatamerous, flexible calyx combining the lower ossicles

3) They have leathery tegmen containing calcareous particles or small plates.

4) They have exposed mouth and ambulacral groove.

Characteristics of class Crinoidea.

1)     They exist in two forms namely extinct form and living form.

2)     The living members are without stalk and free moving  but the extinct forms are attached by stalk.

3)     They have body which consist of an aboral cup , the calyx and oral cover or roof, the tegmen and are pentamerous in structure.

4)     They have oral surface directed to upwards.

5)     They have mouth usually at centre, anus away from centre present on the oral surface.

6)     They have simple, mostly branched movable arms, usually five or ten in numbers with or without pinnules.

7)     They have opened ambulacral grooves which are extended along arms and pinnules to their tips.

8)     They have madreporite, spine and pedicellariae  present on them.

9)     They are commonly called sea lily.

10)  They have sex organs in two reproductive bodies.

classes and orders of echinodermata

This classification is based on Hyman done in 1955.He has described the classes and orders of echinodermata which are existing on earth.According to him there are five classes of echinodermata that are listed here with the words that form the class and orders and examples.

    Class1:-Crinoidea  (Gr.,crinon=lily+eidos=form)

                  order:- Articulata

                  Examples:-Antedon, Rhizocrinus, Metacrinus

Metacrinus

Rhizocrinus

  































Class2:-Holothuroidea( Gr.,holothurion=waater polyp+eidos)

                  order1:-Aspidochirota

                  Examples:-Holothuria,Stichopus,Mesothuria

Mesothuria intestinalis

Holothuria tubulosa

Stichopus tremulus

Stichopus

              




  





























  
















order2:-Elasipoda

                 Examples:-Deima, Benthodytes

Benthodytes

Benthodytes

Deima

Deima

                  


order:3-Dendrochirota

                 Examples:- Thyone,Cucumaria,Phyllophorus

Thyone-fusus

Thyone -

            

cucumaria frondosa

cucumaria miniata

cucumaria piperata

cucumaria planci

cucuaria pulcheerima

      








order4:-Molpadonia

                 Examples:- Molpadia,Paracaudina

                  order5:-Apoda

                 Examples:- Synapta, Chiridoata

   Class3:-Echinoidea (Gr.,echinos=hedgehog+eidos=form)

                  order:1-Lepidocentroda

                 Examples:-Phormosoma,Sperosoma

                   order2:-Cidaroidea

                 Examples:-Cidaris, Notocidaris

                   order3:- Aulodonata

                 Examples:- Diodema, Astropyga

                   order4:- Camarodonata

                 Examples:-Echinus,Strongylocentrotus

   Class4:-Asteroidea (Gr.,aster=star+eidos=form)

                   order1:-Phanerozinia

                 Examples:-Luidia,Astropecten, Archaster,Pentaceros

                   order2:- Spinulosa

                 Examples:- Aesterina,Echinaster,Hymenater,Solaster

                   order3:-Forcipulata

                Examples:- Brisingaster,Heliater,Zoraster,Asterias

   Class5:- Ophiuroidea (Gr., ophis=serpent+oura=tail+eidos=form)

                   order1:-Ophirae

                 Examples:- Ophioderma,Ophioscolex,Ophiothrix

                   order2:-Euryalae

                 Examples:-Asteronyx.Astrophyton,Astoporpa

Characteristics of Echinodermata

1) They are found in sea and are most common and widely distributed.

2) They are found in all seas from the intertidal zone to the great depth.

3) They are usually radial symmetry always pentamerous

4) They have triploblastic body,without clearly differentiated head and segmentation.

5) They have round to cylindrical or star shaped with simple arms radiating from central disc or branched

    feathery arms arise from a central body .

6) They are medium sized to considerable size but non are microscopic.

7) They have body covered by five symmetrical spaced radiating grooves called ambulacra with five alternative inter -radii or inter ambulacra.

8) They have endoskeleton consisting of closely fitted plates which form a shell called theca or test or made

   up of separate ossicle.

9) They have spacious coelom which is lined by peritoneum and is occupied by digestive and reproductive

    system.The peritoneum is developed from embryonic archenteron.

10)They have water vascular or ambulacral system consisting of tubes filled by watery fluid.

11) They have coiled tube alimentary canal extending from mouth that is located on the oral surface to the anus on the aboral or oral surface.

12) They have circulatory system or haemal system or blood lacunar system in their body.

13) They breath through papulae,peristomial gills, genital bursae and cloacal respiratory trees.

14) They have primitive nervous system which consists of networks gathered into the radial ganglionated nerve cords.

15) They do not have well developed sense organs.

16) Most of them have sex organs in two separate body except few of them.They have simple gonads with or without simple ducts.

17) They usually reproduce sexual but few reproduce asexually by regeneration.

18) They have fertilization taking place externally but few of them also are viviparous .

 

Introduction of Echinodermata

The word echinodermata is derived from two Greek words echinos which means hedgehog and derama which means skin. These are animals which are mostly marine living on the shore but mostly on the bottom of the sea.

These are animals whose body can be divided into five parts arranged around a central axis but its larva is divided into two equal parts.These are animals which consists of calcareos exoskeleton. These animals have separate sexual organs and no copulation takes place .The gonads discharge their gametes to outside and fertilization takes place in the sea water.

                                             Echinodermata are widely distributed and contains 5300 species.The phylum is divided into two sub phyla namely Pelmatozoa and Eleutherozoa. The Pelmatozoa has only one living class called Crinoidea while Eleutherozoa has four living class namely Holothuroidea, Echinoidea, Asteroidea and Ophiuroidea

F) characteristics of phylum Diplopoda:

   1)  It includes animals with thousand legs or millipedes.

   2)  Its  body is cylindrical, subcylindrical, elongated and capable of being 
      rolled up.

  3)  Body is divided into three parts head, thorax and abdomen.

  4)  Head consist of five segments, thorax of four segments and abdomen of 
       20 to 100 segments.

  5)  Head has a pair of antennae , one pair of mandible and a pair of maxillae.

  6) Each thorax segments has a pair of legs while each abdominal segments

       bear two pairs of legs.

  7)They do not bear poison claws.

  8)     They are herbivorous in feeding habit.

  9)     They have gonopores mid-ventrally situated on 3^rd abdominal segment.

E) characteristics of phylum Insecta:

 1)  Insects are air breathing mostly terrestrial and rarely aquatic arthropods.

 2) Body is divided into three distinct regions head ,thorax and abdomen.

 3) Head consists of six fused segments and bears a pair of antennae and mouth   
    parts adapted for chewing, biting, piercing , sucking ,siphoning or Sponging type.

 4) Thorax consist of three free segments,each bearing a pair of legs and two pairs of
     wings borne on the second and third segments.

5) Abdomen consist of 7to 11 segments and without appendages.

6) Liver is absent  but salivary glands are usually present.

7) Heart is elongated , tubular and is divided into eight chambers situated in the  
   abdomen.

8) Respiration is carried by branched tracheae.

9) Excretion is carried by Malphigian tubules.

10) Sexes are separate.

C) Characteristics of phylum Symphyla

1)     It includes garden centipede.

2)     It is terrestrial animal also found in damp places with humus.

3)     Body is divided into head and trunk.

4)     The head has a pair of antennae, one pair of mandibles and two pairs of maxillae.

5)     Trunk consist of 12 segments with one pair of legs in each segment.

6)     Spiracles are present in head only but eyes are absent in it.

7)     Genital apertures (reproductive pore)are situated mid ventrally between 4^th pair of legs.

Examples:- Scutigerella, Scolopendrella.

B) Characteristics of phylum Chilopoda

1)     Body is flattened dorso-ventrally and long.

2)     Body is divided into head and trunk.

3)     The head of it has a pair of antennae, a pair of mandibles a pair of maxillae.

4)     The trunk is segmented with a pair of legs.

5)     The first pair of legs is modified into poison claws.

6)     They are  carnivorous ,active and hunt their prey.

A) Characteristics of crustacean( L-crusta=hard shell)

1)     They are mainly aquatic,generally marine but few freshwater and few live in moist places.

2)     They are generally free living but few are parasitic forms.

3)     Their head are often fused with thorax to form cephalothorax covered dorsally by carapace.

4)     Head bears a pair of compound eyes and five pairs of appendages.

5)     Thorax and abdomen are often with a pair of biramous appendagesi n each segment. The appendages are modified for various functions.

6)     Respiration is either by gills or general body surface.  

7)     Coelom is greatly reduced  in the form haemocoel.

8)     Blood vascular system includes a dorsal contractile heart .

9)     Excretory organs are either maxillary glands or antennary glands.

10) Sexes are usually separate. Sexual dimorphism is common.

11) Development occurs by metamorphosis with free larval stage.

Classification of Arthropoda

           The phylum Arthropoda has been classified in to different way by different zoologist but now we follow the classification given by the three zoologist names

Vandel(1949), Snodgrass(1960)and Storer(1979). At the starting Onycophora was considered as Arthropods but now it is given as separate group of segmented animals.

    Atlogether according to modern classification the arthropoda has been divided into 6 grops. They are 1)Crustacea  2) chillopoda  3) Symphyla  4) Pauropoda

5) Insecta 6) Diplopoda

Characteristics of Arthropoda:

1)     Arthropds are triploblastic ,bilaterally symmetrical , metamerically segmented                                                       animals.

2)     Body is covered with a thick chitinous cuticle forming an exoskeleton.

3)     Body segments usually bear paired lateral and jointed appendages

4)     Muscle is not continuous but comprises separate striped muscles.

5)     Body cavity is haemocoel. The true coelom is reduced to the spaces of the genital and excretory organs.

6)     Digestive tract is complete. Mouth and anus lie at opposite ends of the body.

7)     Circulatory system is open with dorsal heart and arteries but without capillaries.

8)     Respiration occurs through general body surface, by gills in aquatic forms, tracheae or lungs in terrestrial forms.

9)     True nephridia are absent. Excretion takes by coelomoducts or malpighian tubules or green or coxal glands.

10)Cilia are absent from all the parts of the body.

11)Sexes are generally separate and sexual dimorphism is often exhibited by several forms.

12)Fertilization is internal. Development is usually indirect through larval stages.

13)Parents take care of the young one  in many arthropoda.