Animals that do not have a notochord are called non-chordata. Non-chordata make up about 95–97% of the world’s population. The characteristics of non-cordata are –
1. Notochord absent.
2. Nerve cord is glandular, digitate and sterile
3. Hemoglobin is present in plasma.
4. Absent hepatic portal system.
5. Eyes are formed from the skin.
6. The circulatory system is dorsal.
7. Flowers and stems absent.
8. True tail and endoskeleton absent.
9. Appendages have more than two pairs.
10. The anus is not posterior to the tail.
11. Cardiac apparatus present or absent on surface of alimentary canal
Phylum Porifera
The word Porifera is derived from the Latin word porous meaning pore and ferro meaning. They are called spore-bearing animals. The animals of this phase are known as sponges. Animals of this phase are called living pumps. The number of species in this category is about 8,659. Robert Grant (1836) named this group Porifera.
Characteristics of the circulation phase
1. They are the simplest multicellular organisms and are immobile.
2. Their body wall has numerous openings called ostia.
3. The body contains flagellated cells called koanocytes.
4. The body has a cavity called spongocele or paragastric. Each spongocele has a single pore called an osculum.
5. The body does not have well-organized organs, organs or systems.
6. They have a duct system in their body. There are three types of canal system. Ascon type, cycon type and leucon type. It functions in respiration and water flow.
7. Endoskeleton composed of spicules or spongy fibers. Spicules are composed of lime and spongy collagen proteins.
8. The body wall consists of 3 layers. Pinoderm on the outside, mesenchyme in the middle and choanoderm on the inside.
9. The matrix in the middle of the body wall contains a gelatinous protein called mesohyl. This matrix contains amoebocytes and skeletal material.
9. Food, oxygen, and sperm enter the ostia through water currents.
10. They are bisexual and reproduce both sexually and asexually. Asexual reproduction occurs by buds or gameules.
11. The life cycle consists of amphiblastula or parenchymula larvae.
Classification of Porifera
The order Porifera is divided into 3 classes.
1. Calcarea: They are small in size and pale in color. Spongin is less. Their skeleton is made of calcium carbonate. They are quite fragile in nature. For example – Sycon gelatinosum.
2. Hexactinellida: These are cup or vase shaped sponges. Large in size. Their spicules are made of silica. Exopinacoderm absent. For example – Euplectella aspergillus.
3 Demosponges: They look like cups or vases and are large. Their choanocytes are narrow. Spicules are made of silica. For example – Spongilla locustris.
Animals of the order Porifera
Scypha gelatinosum
Spongilla – Spongilla lacustris
Bath sponge – Spongilla officinalis
Freshwater sponge – Spongilla proliferan
Clathrina – Clathrina lacunosa
Leucosolenia – Leucosolenia complicata
Euplectella – Euplectella aspergillus
Chalina – Chalina oculata
Hyalonema – Hyalonema longissimum
Euspongia – Euspongia officinalis
Chiona – Chiona celata
Grantia-Grantia compressa
Neptune Cup – Poterion neptuni
Ostia
Ostia means hole. Ostia are the tiny openings on the outside of the body of peripheric animals. Water enters the body through the ostia. For example – Scypha (Scypha gelatinosum).
spongocoel
A spongocele is called a paragastric cavity. The body cavity of peripheric animals is called spongocele. The opening of spongocele is called osculum. The spongiocele holds water and exits the body through the osculum. For example – Spongilla (Spongilla lacustris).
Choanocyte
Cells with goblet-shaped flagella in the bodies of protozoa are called choanocytes. It resides within the walls of the ducts. It controls the flow of water.
Spicule
The tiny spines that make up the body structure of animals of the peripheries phase are called spicules. It is composed of lime or silica. It is a hard material. Neptune Cup (Poterion neptuni).
Cnidaria Phylum
The word Cnidaria is formed by combining the Greek word knide meaning thorn and the Latin word area. Nidarians are called flower of the sea. The former name of the order Nidaria is Cilenterata. The marine animal Chironex fleckeri is the world’s most poisonous jellyfish (it can kill 67 people). Animals of this phase form colonies under the sea like a tropical rain forest. They form reefs or reefs. The number of species in this category is about 10,203. Cnidaria was named by scientist Leuckart (1847).
Characteristics of Nidaria phase
1. They are diploblastic animals. That is, their cells have two cell layers called ectoderm and endoderm.
2. Between the ectoderm and endoderm is an acellular layer called mesoglia.
3. Their body shape is filamentous, tubular and umbellate.
4. The body consists of nidoblast cells, which bear nematocysts.
5. There is a body cavity called gastrovascular or cilantern. The cilianteron is called the alimentary canal. It acts as the mouth and anus and participates in digestion and transport.
6. Cellular and organelle division of labor is seen.
7. The life cycle includes genetics, metagenesis and polymorphism.
8. In the life cycle there are stationary polyp dasa and active medusa dasa.
9. Body does not have organ system, respiratory system and circulatory system. The nervous system is underdeveloped.
10. They are multicellular, asymmetrical and headless.
11. Food material is digested extracellularly and intracellularly.
12. Respiration occurs through ciliated planula larvae.
13. Twenty species of Nidaria are freshwater. The remaining Nidaria are marine.
Characteristics Key words to remember: diploblastic, mesoglia, nidoblast, coelenteron, division of labor, metagenesis, polymorphism, polyp, medusa]
Classification of Cnidaria
The order Cnidaria is divided into 4 classes.
1. Hydrozoa: They live in water. Polyp or medusa stages are seen in the life cycle. Mesoglia are cellless. Genitalia arise from ectoderm. Like- Hydra viridis, Obelia geniculata.
2. Scyphozoa: These are cup or bell or umbrella shaped animals. Medusa Dasha is the main one in the life cycle. Genitalia arise from endoderm. Mesoglia are large and composed of cells and fibers. For example, Aurelia aurita
3. Cubozoa: They are storm-like creatures. Their Medusa Dasa is the main one. For example, Metridium
4. Anthozoa: They are flower-shaped organisms. A polyp stage is present in the life cycle. Mesoglia are composed of fibrous connective tissue. Genitalia arise from endoderm. For example, Metridium senil, Gorgoni verrucosa.
Some animals of the order Nidaria
Hydra – Hydra vulgaris
Chlorohydra – Chlorohydra viridissima
Jellyfish – Aurelia aurita
Portuguese Man of War – Physalia physalis
Adamsia – Adamsia palliata
Obelia- Obelia geniculata
Sea fan – Gorgonia ventilina
Sea feather – Pennatula aculeata
Sea saffron – Metridium senile
Carydea- Carybdea alata
Cyanea – Cyanea capillata
Chironex – Chironex fleckeri
Brain Coral – Meandrina meandrites
Gorgonia- Gorgonia verrucosa
Red Coral – Corallium rubrum
Kamangola jelly – Stomolophus meleagris
Jelly fish
Jellyfish are marine animals belonging to the order Nidaria. It consists of a hanging part called manubrium. There are four oral arms with shafts. Numerous hollow cores exist. For example – Aurelia aurita.
Platyhelminthes
The word Platyhelminthes is formed from the Greek words platy meaning flat and helminth meaning worm. Animals of this group are known as flatworms or tapeworms. The number of species in this category is about 29,487. The group Platyhelminthes was named by the scientist Gagenbaur (Gagenbaur, 1859). Some flatworms of the genus cause schistosomiasis or snail fever in humans.
Characteristics of Platyhelminthes phase
1. They are triploblastic animals. That is, the body has cell layers called ectoderm, endoderm and mesoderm.
2. The body is bilaterally symmetrical and flattened like a leaf or ribbon.
3. They are Asilomates. Between different organs are parenchyma or collenchyma cells.
4. Body skin is soft, without cilia or cuticles.
5. The mouth has suckers or hooks or proglottids.
6. The excretory system is made up of flame cells.
7. The nervous system is ladder-like and consists of ganglia and digitorum plexus.
8. Their epidermis is composed of syncytes.
9. Circulatory system and respiratory system are absent.
10. Alimentary system is incomplete, branched and consists of mouth, pharynx and intestine. There is no anus.
11. They self-destruct. The life cycle consists of larvae such as radia, cercoria, sporocysts, cysticercus etc.
[Key words to remember characteristics: triploblastic, flattened, parenchyma, autophagic, sucker, hook, flame cell, syncytial]
Classification of Platyhelminthes
The order Platyhelminthes is divided into 4 classes.
1. Turbellaria: Their bodies are flat like leaves. Cuticle is absent on the body. The epidermis is ciliated and rhabdite in nature. Suction is missing. Larval stage absent. They are known as Edewam. Such as Planaria (Dugesia tigrina).
2. Trematoda: They are cylindrical or flat like leaves. Cilia are absent on the body. The mouth has suckers or hooks. Larval stage present. They are known as Fluke. For example- liver worm (Fasciola hepatica).
3. Monogenia: These are small parasites. Their heads contain nerve cells and sensory organs. Alimentary canal is simple in nature. They are known as flatworms. Such as Planaria (Dugesia tigrina).
4. Cestoda: Their bodies are long and flattened like ribbons. Composed of 800-900 proglottid segments. Each segment has one or two sets of male or female reproductive organs. The mouth has suckers and curved hooks. Mouth opening and esophagus absent. They are known as tapeworms. For example, tapeworm (Taenia solium).
Flame cell
The cyst is a part of the excretory organ. Cells are bulbous with holes. It is attached to the tube of mesoderm. It has cilia in clusters. The cilia vibrate violently inside the tube, creating a current of water. As a result, the waste material is released through the excretory hole. Thus it helps in digestion.
Some animals of the order Platyhelminthes
Liver worm- Fasciola hepatica
Tape worm – Taenia solium
Dog tapeworm – Echinococcus granulosus
Free-living flatworm – Dugesia tigrina
Hammer head worm- Bipalium kewense
Human bloodworm – Schistosoma mansoni
Frog worm- Polystoma integrimum
Gyrodactylus- Gyrodactylus corti
Dactylogyrus alatus
Convoluta- Convoluta convoluta
Microstomum- Microstomum lineare
Thysanozoon – Thysanozoon brocchii
Sheep worm- Dicrocoelium dendriticum
Nematoda Phylum
The word Nematoda is formed from the Greek words nematos meaning thread, eidos meaning shape and helminth meaning worm. Those organisms whose bodies are cylindrical, cuticular, segmentless, bilaterally symmetrical and have irregular cilia are called nematodes. The animals of this phase are known as threadworms or roundworms. The structure of the body is like a ‘tube within a tube’. They cause ascariasis, elephantiasis, conjunctivitis, abdominal pain, trichuriasis etc. in human body. They play an important role in the nitrogen cycle. 90% of species under the sea are nematodes. The number of species in this category is about 25,033. Previously they were known as Nemathelminthes or Aschelminthes. The order Nemathelminthes was named by scientist Gagenbaur (1851).
Characteristics of Nematoda phase
1. Body long, cylindrical, bilaterally symmetrical, narrow at both ends and wide in the middle. Known as roundworms.
2. Body unsegmented, ciliated and covered with thick cuticle.
3. The body is flexible and made of elastin.
4. Abnormal cells are present in the body.
5. They are unisexual and sexually dimorphic.
6. The alimentary canal is complete, straight, unbranched and extends from the mouth to the anus. So the structure of the body looks like a tube inside a tube.
7. The mouth opening is surrounded by characteristic mucus.
8. Respiratory and circulatory systems are absent.
9. A rhabditiform or microfilariae larval stage exists in the life cycle.
10. They are terrestrial or aquatic, free-living or parasitic.
Classification of Nematoda
The order Nematoda is divided into 2 classes.
1. Secernentia/Phasmedia: Their phasmids are present. Having pore-like amphids. Excretory system present. For example – round worm (Ascaris lumbricoides).
2. Adenophores/Aphasmedia: Their phasmids are absent. Amphids are not pore-like. Caudal gland present. Eg – Whipworm (Trichinella spiralis).
Some animals of Nematoda order
Roundworm – Ascaris lumbricoides
Eye worm – Loa loa
Hook worm – Ancylostoma doudenale
Hook worm – Necator americanus
Mealworm – Enterobius vermicularis
Ringworm- Wuchereria bancroftis
Whipworm – Trichinella spiralis
Trichuris trichiura
Dioctophyme – Dioctophyme renale
Free-living roundworm – Caenorhabditis elegans
Phylum Mollusca
The word Mollusca is derived from the Latin word molluscus meaning soft. Mollusca are the animals whose body is soft, asymmetrical or bilaterally symmetrical, segmentless, ciliated, fleshy legs and exoskeleton made of calcium carbonate. Mollusca is the second largest phylum of fauna. But it is the largest marine episode. 23% of the ocean is molluscs. Precious pearls, Tyrian purple dye, sea silk, lime etc. are obtained from animals of this phase. The giant squid of this episode is 12 meters long and weighs 270 kg. Land snails (Achatina fulica) and snails cause extensive damage to crops and are known as crop pests. The number of species in this category is about 1,00,000. Johnston (1650) named the order Mollusca.
Characteristics of the Mollusca phase
1. Their bodies are soft, fleshy and unsegmented.
2. They are cylomates, asymmetrical or bilaterally symmetrical and have a conspicuous head.
3. At the base of the body are muscular fleshy legs.
4. The body is covered by a thin covering called mantle. Calcareous material secreted from the mantle forms the shell.
5. Respiration occurs by gills and mantle membrane. Pulmonary sacs are developed in terrestrials.
6. The digestive tract consists of sand-tongues or radulas made of chitin.
7. The body cavity is very short and turned into a hemocele. Circulatory system is semi-free type.
8. The alimentary canal is straight, curved or U-shaped.
9. Blood contains hemocyanin (meat and copper) and amoebocytes.
10. Siloam is limited only to the sides of the heart, the genital cavity and the kidneys.
11. A unisexual or bisexual animal. They have sex.
12. The life cycle consists of trochophore, velizar or gochidium larvae.
13. They live in sea salt water, fresh water, ditches or pits.
Classification of Mollusca
The order Mollusca is divided into 5 classes.
1. Caudofovita: They are 2–140 mm long. Body covered with chitinous cuticle. They are marine.
2. Polyplacophora: They are 8 mm to 33 cm long. Body covered by chitin.
3. Gastropods: Their bodies are soft, fleshy and unsegmented. Body covered by mantle.
4. Bivalvia: They have hemolymph fluid. There are two shells made of calcium carbonate.
5. Cephalopoda: These are marine animals with eight arms. There is no hard shell on the body. Has eight legs (cephalopods). They are nocturnal.
Some animals of the order Mollusca
Snail – Pila globosa
Octopus – Octopus macropus
Mussel – Lamellidens marginalis
Dentalium – Dentalium kernedei
Loligo – Loligo edulis
Cattle fish – Sepia aculeata
Neopilina – Neopilina galatheae
Teredo – Teredo navalis
Mussel – Unio marginalis
Pearl oyster – Pinctada vulgaris
Chiton – Chiton tuberculatus
Chiton – Ischnochiton evanida
Chaetoderma – Chaetoderma nitidulum
Solen – Solen ensis
Garden Snail – Helix pomatia
King Scallop – Pecten maximus
Devil fish
Eight armed marine animals belonging to the Mollusca family are called devil fish. It is called Octopus. They grab prey by their arms and kill them with poisonous saliva secreted from their mouths. For example – Octopus macropus.
Cuttle fish
Sepia and Loligo belong to Mollusca group called cuttlefish. Cuttlefish are edible animals. Their body is shield-shaped. Shells exist on the body. For example – Sepia aculeata.
Radula
The radula is a sand tongue. The radula or sand tongue is a toothed tongue-like organ in the digestive system of molluscs. It is made of chitin. It helps in taking and chewing food. For example – Snail (Pila globosa).
Ctenidia
Pteridia are respiratory organs. The gill-like breathing organs in the molluscs are called taenia. It resides in the mantle or mantle cavity or on the body surface of animals.
Phylum Annelida
The word Annelida is derived from the Latin word annelus meaning small ring and eidos meaning shape. Animal bodies that are triploblastic, cylindrical, ring-like segments or metameres are called Annelida. The animals of this phase are known as ringworms or segmented worms. Phlebotomy is the process in which a starved leech is attached to the body to suck the contaminated blood from the body. The number of species in this category is about 17,338. Lamark (1809) identified soft-bodied animals as Annelida.
Characteristics of the class Annelida
1. Body long, cylindrical, bilaterally symmetrical and with true cylomes.
2. The body is segmented and composed of many segments or metameres similar to rings.
3. Movement organs are chitinous CT or parapodia.
4. Patchy excretory organs called nephridia are located in almost every segment. It is called segmental organ.
5. The body contains the clitellum and secretes mucus.
6. The alimentary canal is cylindrical and complete and consists of oral and anal openings.
7. Blood is red. Plasma contains hemoglobin, heme-erythrin or chloroquine.
8. The body is composed of chitinless and soft cuticle.
9. The larval stage of the life cycle consists of trochophores.
10. They are unisexual or bisexual. Reproduction occurs sexually and asexually.
Classification of Annelida
The order Annelida is divided into 3 classes.
1. Polychaeta: Their body parts are covered with hairs. locomotion parapodia. Sensory organ is nucell organ. They are mostly marine. For example, Nereis caudata.
2. Oligochaeta: These are leech-like creatures. They live by digging holes. For example, Metaphire posthuma.
3. Hirudinia: They have clitellum. There is a substance called hirudin in the body. For example, Hirudinaria medicinalis.
Some animals of the order Annelida
Leech- Hirudinaria medicinalis
Nereis- Nereis/Neanthes caudata
Spectacular insect – Amphrite figulus
Arenicola – Arenicola marina
Earthworm- Metaphire posthuma
Terebella lapidaria
Haemopis- Haemopis terrestris
Pontopdella- Pontopdella muricata
Hairy Worm- Hediste diversicolor
Blood worm- Glycera convoluta
Lumbricus- Lumbricus terrestris
Parchment worm- Chaetopterus variopedatus
Red worm – Eisenia foetida
Tubifex – Tubifex tubifex
Sea Lice – Aphrodite aculeata
Ornate Worm- Aphrodite ornata
Fan worm- Serpula vermicularis
Nephridia
Nephridia is a type of excretory organ. nephridia It collects nitrogenous wastes. Passes waste material to the intestines. Plays a role in osmoregulation.
Phylum Arthropoda
The term Arthropoda is formed from the Greek words arthros meaning jointed and podos meaning foot. Those animals whose body has jointed appendages, bilaterally symmetrical, free circulatory system, hemoceles and exoskeleton containing chitin are called Arthropoda. Arthropoda is the largest group of animals. 80% of animals in the fauna are arthropods. The number of species is about 12,57,040. They are herbivores, carnivores or omnivours. Von Siebold (1845) named the order Arthropoda.
Characteristics of Arthropoda
1. They are triploblastic organisms, bilaterally symmetrical and segmented.
2. The body is divided into tagmata. The body is divided into head, thorax and abdomen.
3. They are animals with jointed appendages. The head has a pair of antennae and a pair of antennae.
4. The appendages of the body are changed to form the mouth. It takes food.
5. The exoskeleton is made up of cuticles and regularly sheds or molts.
6. The body cavity is known as hemocele. It is filled with blood.
7. Their main excretory organ is the Malpighian duct. But excretion is also done by green gland, chyloe, coxal gland, antennal gland and maxillary gland.
8. The circulatory system is open type. It consists of the heart, arteries and hemocele.
9. Respiration is accomplished through their trachea, gills, skin, gills, or pectoral fins.
10. Men and women are separate animals. Their internal fertilization occurs. Turns into an explosion.
11. The life cycle consists of larva, pupa and nymph stage.
12. They live as terrestrial, aquatic, sessile, free-living, parasitic or symbiotic.
[Key words to remember features: triploblastic, tagmata, pujakshi, moulting, hemocele, malpighian duct, chest lung]
Classification of Arthropoda
The order Arthropoda is divided into several suborders.
1. Trilobitomorpha: These are invertebrate arthropods. Their exoskeleton is strong. They are the most diverse.
2. Crustacea: Their bodies are soft and three-layered. Real Siloam exists. Has two pairs of antennae. Has two compound eyes. The body is divided into segments. For example – Bagda shrimp (Penaeus monodon).
3. Calicerata: These are eight-jointed joints. The body is divided into head and torso. They don’t have wings. There are poison glands in the body. For example – Spider (Lycosa lenta)
4. Hexapoda: Their body is chitinous and divided into head, thorax and abdomen. The thorax has a pair of jointed legs and a pair of wings. Has a branched tracheal system. Respiration is done by air ducts. Free circulatory system exists. Excretion is accomplished by the Malpighian duct
Some animals of Arthropoda order
Flies – Musca domestica
Lobster- Macrobrachium resenbergii
Shrimp – Penaeus monodon
Cockroach- Periplaneta americana
Horse-hoofed crab – Tachypleus tridentatus
Limulus- Limulus polyphenus
Mosquito – Culex pipiens
Dengue mosquito- Aedes aegypti
Bee – Apis mellifera
Spider- Lycosa lenta
Grasshopper – Oxya chinensis
Butterfly – Papilio xuthus
Centipede- Scolopendra laeta
Thousand feet – Julus terrestris
Crab- Scylla olivacea
Beetle- Scolopendra gigantea
Barnacle – Balanus balanus
Hunting Mantis – Mantis religiosa
Bookworm- Lepisma saccharina
Buthus- Buthus tamulus
How to Identify Butterflies
1. The body of the butterfly is thin and covered with soft hairs.
2. The pupa of the batyfly resides within the chrysalis.
3. Adults have slender antennae and head discs.
4. When sitting, the fins are erect.
Haemocoel
A body cavity filled with hemolymph is called a hemocele. It is divided into three chambers or sinuses by the dorsal membrane and digital membrane. Pericardial sinus above the dorsal membrane, perivisceral sinus below the dorsal membrane and perineural sinus below the ventral membrane.
Book lung
The chest and lungs are organs of the body. The outer skin of the digital floor of Arthropoda animals is folded and arranged like the pages of a book to form the respiratory organ called the book lung. Spider (Lycosa lenta).
Book gill
The chest gill is a sexual organ. In Arthropoda animals, the skin of the digital floor is folded and forms a breathing organ like a gill like a page of a book is called a chest gill. For example – Macrobrachium resenbergii.
Tagmata
Each region of the body of animals of Arthropoda class is called tagmata. The process by which the animal body is divided into tagmata is called tagmatization. The evolutionary process by which tagmatization is accomplished is called tagmosis. The bodies of animals of the class Insecta of the order Arthropoda are divided into three tagmas. Namely – head, chest and abdomen. For example, grasshopper (Poekilocerux pictus).
Ectoprocta/Bryozoa Phylum
Characteristics of the phylum Bryozoa
1. They are colonial and look like moss plants.
2. They stick to submerged solids.
3. Each member of the colony is called a zooid. Zooids live in burrows called zoeciums.
4. Their bodies consist of polypides (lophophores) and cystids. Polypides consume food and form the exoskeleton of the cystid body.
5. The organ that surrounds the mouth is called lophophore.
6. On the outside of the lophophore is the anal pore.
Some animals of the order Bryozoa
Electra – Electra bengalensis
Antropora – Antropora minor
Crisia – Crisia eburnea
Pectinatella – Pectinatella magnifica
Phylum Echinodermata
The word Echinodermata is formed from the Latin words Echinus meaning prickly, derma meaning skin and ata meaning bearing. Animals whose body is symmetrical, five-segmented, ciliated, headless, circulatory system and echinodermata are called Echinodermata. They are called conifers. Animals like sea star, sea cucumber, sea lilies, sea urchin, sand dollar etc. belong to this phase. The number of species is about 7,550. Jacob Klein (1734) named Echinodermata.
Characteristics of the group Echinodermata
1. Their bodies are unsegmented, cylindrical or spherical or star-shaped or flower-shaped.
2. Their body is bilaterally symmetrical or pentalaterally symmetrical or orally symmetrical or divided into five equal parts.
3. Body skin prickly. The exoskeleton is composed of numerous ossicles composed of spines and pedicellaries and the endoskeleton composed of calcium carbonate. It is covered by ciliated membranes.
4. The body is organized into distinct verbal and non-verbal levels. Five ambulacral grooves are present on the oral floor.
5. They have a water circulatory system, which carries out respiration and locomotion.
6. There are ring vessels, radial canals, medriporites, stone canals and lateral canals for water transport.
7. Their moving parts are podia. It is responsible for respiration and food absorption.
8. The Himalayan and Perihimalayantra work on circulation.
9. The body does not have a brain, respiratory system, excretory system and circulatory system.
10. All animals are marine.
11. The life cycle consists of bipinaria, auricularia, ophiopluteus, echinopluteus larvae.
Classification of Echinidermata
The order Echinidermata is divided into five classes.
1. Asteroids: Their bodies are star-shaped with five arms. Tube fit exists. Spines and pedicilli are present on the body. For example – sea star (Asterias vulgaris).
2. Ophuroidea: Their bodies are pentamerous discs. Tube fit and spine present on the body. Their arms are long. For example – Cucumaria (Cucumaria planci).
3. Echinoidea: Their bodies are hemispherical. Tube fit exists. The body has no arms. Spine present. For example, sea urchin (Echinus esculentus).
4. Holothuroids: Their bodies are long cylindrical in shape. The body has no arms, spines and pedicellariae. But tube fit exists. For example, sea cucumber (Holothuria impatiens).
5. Crinoid: Their bodies are star-shaped. The body does not have tube feet, spines, pedicillaries etc.
Some animals of the order Echinodermata
Sea cucumber – Holothuria impatiens
Pink feather star – Antedon bifida
Brittle Star – Ophiothrix fragilis
Sea stars- Asterias vulgaris, Astropecten euryacanthus
Snake star- Ophiura ciliaris
Sea urchin- Echinus esculentus
Cucumaria- Cucumaria planci
Sea daisy- Xylopax medusiformes
Gorgonocephalus – Gorgonocephalus arcticus
Bristle star- Ophiocoma scolopendrina
Sea pentagon- Oreaster reticulatus
Aka sea star – Anthenea pentagonula
Water vascular system
A water circulation system is a water-filled cavity. Animals of the order Echinodermata have various shaped tubes filled with water inside the body called water circulatory system. A water circulation system is created by changing parts of the silo. It transports various types of objects through it.
Ambulacral groove
A shallow groove along the digital midline of each arm is called an ambulacral groove in the phylum Echinodermata. These grooves arise from each side of the five corners of their mouth. For example, sea star (Asterias vulgaris).
Tube feet
Tube fit is the moving part. The body of animals of the order Echinodermata is equipped with two rows of tubes called tube feet. Tube feet are narrow, hollow, muscular and elastic. Tube fits occur along the length of the ambulacral groove. For example, sea star (Asterias vulgaris).
Star fish
The star-shaped animals of the order Echinodermata are called starfish. They look like stars as they have five arms. Such as Asterias vulgaris, Astropecten euryacanthus, Ophiura ciliaris.