1. Sub Phylum Chelicerata
Aquatic Terrestrial
Araneae
Class
Arachnida
Class Merostomata
Acari
Ticks, mites
Scorpiones
Class Pycnogonida

3. Eurypterids 450 to 250 mya (water scorpions)
Largest arthropods ever known (largest nearly 3 m)
Many features in common with modern scorpions
and horse-shoe crabs
With book gills similar to those in horseshoe crabs

4. Eurypterids 450 to 250 mya
Largest arthropods ever known (largest nearly 3 m)
Many features in common with modern scorpions
and horse-shoe crabs
Xiphosura
Arachnida
Pycnogonida
Eurypterida
Water scorpions invaded estuaries, fresh water, and are believed to be ancestors of arachnids
Ancestral
chelicerate

5. are also arachnids but distantly related
vinegaroon
Microwhip
scorpion
Spiders
Whip scorpions
False scorpions
True scorpions
are also arachnids but distantly related

6. Permian Arachnids
332 mya
With silk producing spigots but lacking spinnerets
Segmented whip; links the spiders to whip scorpions

7. Chelicerata Body Plan Order Araneae as a model
Body as anterior prosoma and post. Opisthosoma (abdomen)
First anterior segment with no appendages
Second segment with clawed “chelicerae” (or fangs)
Other head appendages are “pedipalps”
No mandibles

8. Internal Morphology of Spiders
Circulatory system, respiration

9. Internal view of a book lung showing
high surface area for oxygen exchange

10. The eyes are image-forming
but simple, not compound

11. Internal Morphology of Spiders
Digestive system and excretory system
midgut
Pumping stomach
mouth

12. Phylogeny of Arthropoda
Nearest relatives?
Mono or polyphyletic?
Relationships within the group?

13. Cephalocarida (12 spp) Remipedia (24 spp) -2-4 mm in sediments Blind
No abdominal appendages
2nd antennae behind the mouth?
(as common in embryonic crustacea)
Remipedia (24 spp)
mm in sediments
Blind
Head and trunk
w/42 segments
Swim upside down
hese crustaceans are from 2 to 4 mm (0.079 to 0.157 in) in length, with an elongated body. They have a large head, the hind edge of which covers the first thoracic segment. They have no eyes, presumably because of their muddy natural habitat. The second pair of antennae is located behind the mouth; in all other crustaceans the antennae are in front of the mouth at the adult stage, and only their larvae have antennae that have the same location as adult cephalocaridans.[2]
The mouth is located behind the large upper lip, flanked by mandibles. The first pair of maxillae is very small, and the second pair has the same structure as the following thoracic legs: a large basal part, equipped with outgrowths on the inner side, used in locomotion, a forked inner branch and two outer lobes - referred to as the "pseudoepipod" and the "exopod". The structural and functional similarity between the maxillae and the legs may be a sign of primitive organization; the maxillae are not specialized, as they are in other crustaceans.[2]
The thorax consists of 10 segments, and the abdomen bears a telson but no other appendages.
1 Description
2 Classification
2.1 Godzilliidae
2.2 Micropacteridae
2.3 Speleonectidae
3 Distribution of extant Remipedia
4 References
5 External links
Description
Remipedes are 10–40 millimetres (0.4–1.6 in) long and comprise a head and an elongate trunk of up to forty-two similar body segments.[2] The swimming appendages are lateral on each segment, and the animals swim on their backs. They are generally slow-moving. They have fangs connected to secretory glands; it is still unknown whether these glands secrete digestive juices or venom, or whether remipedes feed primarily on detritus or on living organisms. They have a generally primitive body plan in crustacean terms, and have been thought to be a basal, ancestral crustacean group. However, Fanenbruck et al. showed that at least one species, Godzilliognomus frondosus, has a highly organized and well-differentiated brain, with a particularly large olfactory area which is a common feature for species that live in dark environments.[3]

14. On the Phylogeny of Arthropoda
A monophyletic lineage of the Ecdysozoa clade
Onychophora is the sister group of Arthropoda

15. -Protocerebrum and deutocerebrum also in Onychophora
-But tritocerebrum is a unique character of Arthropoda
-Position of cerebrums helps establish homology of segments and segmental appendages

16. Arthropod Phylogeny Mandibulata and Atelocerata
Mandibulata and PanCrustacea
Chelicerata
Chelicerata
Crustacea
Myriapoda
Myriapoda
Crustacea
Hexapoda
Hexapoda
Homology of mandible widely accepted.
Is possession of uniramous appendages and a single pair of antennae {Atelocerata = without back horns (or antennae)} a shared derived character?
Mandibles
Multiramous appendages
Atelocerata-Uniramia

17. Arthropod Phylogeny Mandibulata and Atelocerata
Mandibulata and PanCrustacea
Chelicerata
Chelicerata
Crustacea
Myriapoda
Myriapoda
Crustacea
Hexapoda
Hexapoda
Homology of mandible widely accepted.
Is possession of uniramous appendages and a single pair of antennae {Atelocerata = without back horns (or antennae)} a shared derived character?
- Insect fossils found with polyramous appendages
- Land Crustacea w/single pair of antennae & uniramous append.
- Buds of second antennae in insect development
- Buds of abdominal appendages in insect development
Mandibles
Multiramous appendages
Atelocerata-Uniramia

18. Mandibulata Chelicerata? Myriapoda? Pancrustacea?
Letter
Nature 463, (25 February 2010)
Arthropod relationships revealed by phylogenomic analysis of nuclear protein-coding sequences
Mandibulata Chelicerata?
Myriapoda?
Pancrustacea?

19. Inferences:
Mandibulata?
Myriapoda?
Hexapoda?
Entognatha?
Insecta?
Crustacea?

20. Homologous Compound eyes indicated by protein
Homologous Compound eyes indicated by protein genetic sequence analysis; evolved in the common ancestor of panCrustacea
- Hemocyanins present in malacostracans also known in cockroaches and grasshopper embryos
JH and Methyl farnesoate production…hormones involved in molting and growth, utilize many of the same enzymes
Have the same set of micro RNAs