sign in sign up
<<
Home , Apterygota, Branchiopoda, Cephalocarida, Entognatha, Mandibulata, Maxillopoda

ARTROPODA CLASSIFICATION

Phylum ARTHROPODA

Arthropods are bilaterally symmetrical, metamerically segmented having chitinous exoskeleton. Moulting is necessary for growth. They possess jointed , a haemocoel or schizocoelom and have open . Segments as well as their appendages are specialized to form various organs. constitute about 80% of all animals.

Subphylum TRILOBITOMORPHA

Fossil arthropods having body divided into 3 longitudinal lobes, one median lobe and two lateral pleural lobes.

Class TRILOBITA

Appendages were biramous and had attached on them. They were abundant during and periods. Body was divided into cephalon, trunk and pygidium. They also possessed segmented antennae and a pair of compound eyes.

Subphylum

First appendages are modified as chelicerae for feeding and second ones modified as pedipalps. Body is divisible into prosoma and , the latter is sometimes divided into and . There are no antennae in these arthropods.

Class MEROSTOMATA

Body is divisible into prosoma, mesosoma and metasoma. They are marine scavengers in which abdominal appendages carry gills and is long spike-like.

Subclass EURYPTERIDA This group includes extinct giant of Ordovician to periods. They had 5 pairs of thoracic swimming appendages and 7 pairs of abdominal appendages which carried 6 pairs of gills. Metasoma was without appendages. Ex. Pterygotus; . They were the dominant predators of the Palaeozoic era.

Subclass

There are only 5 surviving of horse-shoe crabs in the world and hence they are called living . They have 5 pairs of thoracic walking legs which are chelate and armed with spines. There are 6 pairs of abdominal appendages carrying 5 pairs of book gills for respiration. Ex. Limulus or king crab.

Class ARACHNIDA

There are one pair of chelicerae and one pair of pedipalps and 4 pairs of thoracic legs in these arthropods. is without legs. Breathing takes place through the book lungs or tracheal system or both. Ex. Scorpions; pseudoscorpions; ; ticks and .

Class PYCNOGONIDA (=PANTOPODA)

They are commonly known as sea spiders that measure 1-10 mm in length. Cephalothorax is large and segmented while abdomen is highly reduced. Legs long for crawling on the sea bottom. They are carnivores that feed on cnidarians and worms. Ex. Nymphon; Pycnogonus.

Subphylum

Arthropods with strong mandibles for chewing and cutting, or mouth parts are modified for different modes of feeding. They are terrestrial as well as aquatic animals.

Class CRUSTACEA

They possess two pairs of antennae and their body is divisible into cephalothorax and abdomen. Eyes are simple or compound. Appendages are variously modified. 1. Subclass Horse-shoe shaped body without a and eyes. They are marine bottom dwellers having long antennae for gathering. Ex. Hutchinsoniella.

2. Subclass They are small freshwater forms with shield-like carapace and abdomen without appendages. Thoracic appendages are used for respiration. Ex. Apus; .

3. Subclass OSTRACODA Marine and freshwater animals with laterally compressed body enclosed in a bivalve shell. Two pairs of thoracic appendages are present. Feeding and locomotion is performed by head appendages. Appendages also have respiratory function. Ex. Cypris; Cypridina.

4. Subclass Body is divided into head, and abdomen. Head appendages are bushy. Four pairs of thoracic appendages are present. They are filter feeders, found among sand grain in beaches. Ex. Deirocheilocaris.

5. Subclass COPEPODA Body is composed of cephalothorax and abdomen, the latter has no appendages. Single eye is present and there is no carapace. Antennae beat in rotary fashion for swimming. Some are planktonic but a large number are parasitic. Ex. ; Caligus, Monstrilla.

6. Subclass These small arthropods possess dorsoventrally flattened body adapted for ectoparasitic mode of life on fishes. Thoracic appendages are 4 pairs, used for swimming. Maxillae are used for anchoring on host. Maxillipedes are absent. There is a spine for puncturing the skin of fish. Gills are absent and abdomen has respiratory function. Ex. .

7. Subclass CIRRIPEDIA They are marine, either sedentary or parasitic. Compound eyes are absent. Thoracic appendages are 6 pairs and abdomen is rudimentary. They are commonly known as . Ex. ; ; .

8. Subclass Large that have 5-segmented head, 8-segmented thorax and 6-segmented abdomen. Cephalothorax is covered with carapace. Compound eyes are stalked. This group includes 75% of all crustaceans. Ex. Mysis; Squilla; Palaemon; Cancer.

9. Subclass They possess long, segmented and worm-like body divided into cephalon and trunk. Trunk appendages are biramous. Two pairs of maxillae and one pair of maxillipedes are present for feeding. Found in marine caves in Bahamas. Ex. Speleonectes; Lasionectes.

10. Subclass They are parasitic in the of reptiles in USA, Europe and Australia. Body is worm-like with 5 appendages on the anterior side and 2 pairs of hooks for anchoring. Trunk is ringed without appendages. Ex. ; Cephalobena.

11. Subclass They are ectoparasites on deep water crustaceans. There are no appendages in adult which has a bag-like body. Larva is free swimming and bears 6 or 7 abdominal somites and appendages. Adult penetrates the host skin by a mouth tube. They look similar to . Ex. Basipodella; Deoterthron.

Class INSECTA (=)

Body is divided into head, thorax and abdomen. There is one pair of antennae, 3 pairs of legs and both compound and simple eyes. Respiration takes place with tracheal system and excretion with malpighian tubules. They are the only flying arthropods.

1. Subclass (=AMETABOLA) They are primitively wingless that have ectognathous mouth parts and also abdominal appendages. There is no during development and juveniles are similar to adults in morphology as well as habits. Ex. Telson-tails; ; Spring- tails; . There are 4 orders in this group.

2. Subclass (=METABOLA) They are winged insects or lost wings later in evolution. Mouth parts are endognathous and abdominal appendages are absent. Metamorphosis is either partial or complete with a pupal stage. Ex. , ; ; Lice; ; ; ; ; ; -lions; . There are 24 orders within this group.

Class CHILOPODA

Medium to large carnivorous animals that live beneath stones and logs and whose body is dorsoventrally flattened and divided into head and trunk. First maxillipede is modified as poison claw. One pair of mandibles and one or two pairs of maxillae are present. Respiration occurs through tracheal system and excretion with malpighian tubules. One pair of compound eyes and one pair of antennae are present. Ex. Scolopendra; Scutigera.

Class DIPLOPODA

Body is cylindrical, divided into head, collum and trunk. Trunk contains diplosegments with two pairs of legs and ostia. Last segment is legless and carries anus. Slow moving, herbivorous animals that contain repugnatorial glands on the skin to repel enemies. Ex. Julius; Glomeris; Spirobolus.

Class

Found in humus, they are 2.0-10.0 mm long agile arthropods that run about rapidly. Body is divided into head and 14-segmented trunk. Pygidium bears an oval telson and a pair of cerci. Spiracle is single pair on the first trunk segment. Eyes are absent and mouth parts are similar to insects. Ex. Scutigerella. Class

Soft bodied, grub-like arthropods, less than 2.0 mm long, having cylindrical body that contains 12 segments. Eyes are absent and antennae are 3-branched. Mandibles are for piercing and grinding. Found in soil and feed on humus and fungi. Ex. Pauropus.

ARTHROPODA CLASSIFICATION (After Ruppert & Barnes, 1994)

1. Subphylum TRILOBITOMORPHA – The

2. Subphylum CHELICERATA – With chelicerae and pedipalps

Class Merostomata – ex. Limulus

Class Arachnida – Spiders, scorpions, mites and ticks

Class Pycnogonida – Sea spiders

3. Subphylum CRUSTACEA

Class Branchiopoda – fairy , brine shrimps

Class – Copepods

Class Malacostraca – Prawn, Crabs, Lobsters, Shrimps

4. Subphylum

Class Insecta – Dragon flies, Cockroach, Beetles, Bugs, Butterflies

Class Chilopoda –

Class Diplopoda – Class Symphyla – Soft bodied Scutigerella

Class Pauropoda – Soft bodied Pauropus

ARTHROPODA CLASSIFICATION (After Brusca & Brusca, 2003)

1. Subphylum TRILOBITOMORPHA (=TRILOBITA)

2. Subphylum CHELICERIFORMES

Class Chelicerata

Subclass Merostomata – Limulus

Subclass Arachnida – Spiders, Scorpions, Mites

Class Pycnogonida – Sea spiders

3. Subphylum CRUSTACEA

Class Remipedia – Lasionectes

Class Cephalocarida – Hutchinsoniella

Class Branchiopoda – Daphnia;

Class Malacostraca – Squilla; Palaemon; Mysis; Cyamus; Crabs

Subclass Phyllocarida (1 )

Subclass Eumalacostraca (15 orders)

Class Maxillopoda Subclass – Ascothorax

Subclass Tantulocarida – Basipodella

Subclass Branchiura – Argulus

Subclass Pentastomida – Linguatula

Subclass Mystacocarida – Deirocheilocaris

Subclass Copepoda – Cyclops; Monstrilla;

Subclass Ostracoda – Cypris; Cypridina

4. Subphylum HEXAPODA

Class – Orders: , and Collembola

Class Insecta – 30 orders of insects

Subclass – Bristle tails

Subclass – Silver fish

Subclass Pterygota – 28 orders. , termites; cockroach etc.

5. Subphylum

Body contains head and long trunk bearing appendages. All are terrestrial with one pair of antennae. Compound eyes or simple eyes are present. Carnivore or herbivore animals, they include centipedes and millipedes.