Presentation of Arthropod phylogeny and classification. Basics about arthropod taxa and their classification up to order level

1. ARTHROPOD PHYLOGENY AND
CLASSIFICATION
PRESENTED BY : MUZNA KASHAF
ROLL NUMBER : 16261514-030

2. CONTENTS
 Arthropod Phylogeny
 Classification Of Arthropodan Taxa With Symbiotic Members
 Phylum Arthropoda
 Subphylum Trilobitomorpha (Trilobites)
 Subphylum Chelicerata
 Classes of subphylum chelicerata
 Sub Phylum Crustacea
 Subphylum Myriapoda
 Classes of subphylum myriapoda
 Sub Phylum Hexapoda
 Class Insecta
 References

3. ARTHROPOD PHYLOGENY
 Traditionally, arthropods have been included in a single phylum of
metameric, coelomate animals.
 Arthropods share many features with annelids, such as metamerism and
a nervous system consisting of supra-esophageal ganglia, nerves
encircling the esophagus, and a ventral series of segmental ganglia.
 Such similarities led to claims that the two phyla are related and that
arthropods likely evolved from annelid like ancestors, but this idea is not
supported by current research.
 Annelids, molluscs, and several minor phyla, all sharing similar larval
types and protostome development, are now placed in superphylum
Lophotrochozoa.
 Based on 18S ribosomal RNA sequence data, phylum Arthropoda is
considered a member of superphylum Ecdysozoa, i.e., animals that molt,
along with Nematoda and other smaller phyla such as Nematomphora,
Onychophora (wormlike tropical and subtropical organisms), and
Tardigrada (water bears).

4. Fig. ARTHROPOD PHYLOGENY

5. PHYLUM ARTHROPODA
 Bilaterally symmetrical invertebrates with jointed exoskeleton
covering body and appendages.
 Cilia is absent, body is segmented, though segmentation commonly
reduced as a result of fusion.
 Appendages typically specialized for different functions.
 Coelom is greatly reduced.
 Nervous system consists of dorsal brain and a double or single
(fused) ventral nerve cord.
 Eggs are typically rich in yolk and development is highly modified.

6. CLASSIFICATION OF PHYLUM
ARTHROPODA

7. SUBPHYLUM TRILOBITOMORPHA
(TRILOBITES)
 Now extinct.
 Head (or cephalon) composed of 5 segments bearing a pair of
antennae and compound eyes.
 Oval, flattened body composed of cephalon, thorax, and
pygidium, each segmented.
 Each segment bears a pair of similar, branched appendages;
marine.
 Present in Cambrian Period to the end of the Paleozoic Era;
more than 4,000 fossil species known.
Fig. Trilobitomorpha

8. SUBPHYLUM CHELICERATA
 Body divided into prosoma (cephalothorax) and opisthosoma
(abdomen).
 No antennae is present.
 First pair of appendages consists of chelicerae flanking the
mouth.
 In most chelicerates the other prosomal appendages are a pair
of pedipalps and four pairs of legs.
Fig. Spider

9. CLASSES OF SUBPHYLUM CHELICERATA
CLASS MEROSTOMATA
 Large marine chelicerates with book gills on the underside of the opisthosoma.
 Prosoma covered by a dorsal carapace and opisthosoma bears a long terminal spine.
 Has 2 orders, Xiphosura (horseshoe crabs, 4 species) and Eurypterida (Gigantostraca), which
is extinct and includes 200 fossil species from the Paleozoic Era .
CLASS ARACHNIDA (SCORPIONS, SPIDERS, TICKS, MITES)
 Chiefly terrestrial.
 Book lungs and/or tracheae as gas exchange organs.
 Opisthosoma (abdomen) segmented or unsegmented externally and broadly or narrowly
joined to the prosoma.
 Prosomal appendages consist of 1 pair of chelicerae, 1 pair of pedipalps, and 4 pairs of legs.
 Gonopore always on the lower side of second abdominal segment.
CLASS PYCNOGONIDA (SEA SPIDERS)
 Marine.
 Narrow trunk of 4 to 6 segments and greatly reduced abdomen.
 Cephalon (head) with proboscis bearing a pair of chelicerae, palpi, and egg-carrying legs.
 Usually 4 pairs of walking legs attached to lateral projections of the trunk.
 Tubercle with 4 eyes located dorsally between the first pair of legs, no gas respiratory organs
are there.

10. SUBPHYLUM CRUSTACEA
 It includes crabs, shrimp, isopods, amphipods, krill, brine shrimp, copepods,
barnacles.
 Chiefly aquatic.
 Head bearing 2 pairs of antennae, a pair of mandibles, and 2 pairs of
maxillae.
 Trunk is highly variable but commonly covered in part or entirely by a
posteriorly directed fold of the head (carapace).
 Paired appendages biramous, often with 1 branch lost.
 2 stalked or stalkless compound eyes present in most.
 When present, gas exchange organs are gills.
 Mostly marine, but many freshwater species are also present.
 Some isopods terrestrial.
Fig. Carapace of crab

11. SUBPHYLUM MYRIAPODA
 Chiefly terrestrial.
 Segmental appendages primitively unbranched.
 Head appendages comprise a pair of antennae, a pair of mandibles,
and 1 or 2 pairs of maxillae.
 Trunk and appendages variable.
 Respiratory organs are tracheae.
Fig. Millipede and Centipede

12. CLASSES OF SUBPHYLUM
MYRIAPODA
CLASS CHILOPODA (CENTIPEDES)
 Elongated body and many trunk segments, each with 1 pair of legs;
2 pairs of maxillae covered by a large pair of poison claws
representing the first pair of trunk appendages.
 Eyes, if present, are simple ocelli.
 Gonopore is present on last segment.
CLASS SYMPHYLA
 Mouthparts consist of a pair of mandibles and 2 pairs of maxillae.
 12 leg-bearing trunk segments; terminal segment carries a pair of
spinnerets; gonopore is present on fourth segment.

13. CLASS DIPLOPODA (MILLIPEDES)
 Elongated body.
 Trunk containing many diplosegments, each bearing 2 pairs of
legs and spiracles.
 Single pair of maxillae fused to form a flattened plate
(gnathochilarium).
 First 4 trunk segments not diplosegments, and third bears the
gonopores.
 Simple eyes (ocelli) present or absent.
CLASS PAUROPODA
 Branched antennae.
 A pair of maxillae.
 9–11 trunk segments bearing legs and gonopores on third trunk
segment as in diplopods.

14. SUBPHYLUM HEXAPODA
 Subphylum Hexapoda includes the most important class
Insecta.
 Hexapoda means 6 legs.
Fig. Dragonfly

15. CLASS INSECTA
 Body composed of a head, thorax, and abdomen.
 Head bears simple eyes and usually a pair of lateral compound
eyes; 2 pairs of maxillae, the second pair fused (labium).
 Thorax is of 3 segments, each with a pair of legs, and the second
and third usually bearing wings.
 Abdomen of 11 segments without appendages in the adult.
 Gonopore at end of abdomen.
 At least 1 million described species are in this class.
CLASS ENTOGNATHA
 It includes all the wingless insects of the subphylum hexapoda.

16. REFERENCES
• Zhang Z-Q (ed) (2011) Animal biodiversity: an outline of higher-level
classification and survey of taxonomic richness. Magnolia Press, Auckland
• James H. Diaz, in Mandell, Douglas, and Bennett's Principles and Practice
of Infectious Diseases (Eighth Edition), 2015
• Fahrbach, S. E. 2004. What arthropod brains say about arthropod
phylogeny. Proc. Nat. Acad. Sci. 101:3723–3724.
• Marcotte, B. M. 1982. Evolution within the Crustacea, part 2:Copepoda. In
L. G. Abele (Ed.), The biology of Crustacea,vol. 1. Systematics, the fossil
record, and biogeography. New York: Academic Press, Inc., pp. 185–197.
• Martin, J. W., and G. E. Davis. 2001. An updated classification of the
recent Crustacea. Nat. Hist. Mus. Los Angeles Co. Sci. Series. Dec. 14,
2001:i–viii, 1–124.

17. THANKS