Arthropods Flashcards
Arthropoda is a phylum belonging to which superphylum?
Ecdysozoa
What phylum do Ecdysozoa encompass?
Arthropoda, Onychophora and Tardigrada
What 4 extant subphyla can arthropoda be split into?
Hexapoda, Crustacea, Myriapoda and Chelicerata
Marine Crustacea provide the key trophic link between which 2 trophic levels?
Primary producers and higher level consumers
Why are chelicerates called chelicerates?
Due to ‘pincers’ on HEAD
When did arthropods first emerge?
Approx. 540 mya
Defining characters of arthropods
Segmentation, jointed appendages + exoskeleton
What is tagmosis?
the grouping of segments with similar functions/structures
Chelicerates fused head with thorax to form what?
Cephalothorax
what is name for segments of Appendages?
Articles
What is arthropod cuticle made from?
Chitin
What is sclerotization?
Where tanning leads to cross linking and stronger properties of arthropod cuticle exoskeleton
What is ecdysis?
periodic moulting of exoskeleton
What is a negative of moulting?
Vunerability- 80-90% arthropod mortality linked to moulting
What are the 5 major subgroups of chelicerata?
Spiders, scorpions, mites + tcks, horse she crabs, sea spider
Name for group with hexapods and crustacea together?
Pancrustacea
Are crustacea monophyletic or paraphyletic?
paraphyletic
What does paraphyletic mean?
descended from a common evolutionary ancestor or ancestral group, but not including all the descendant groups.
What does polyphyletic mean?
derived from more than one common evolutionary ancestor or ancestral group and therefore not suitable for placing in the same taxon.
What are the major classes of crustacea recognised?
cephalocardia, Malacostracca + maxillopoda (polyphyletic), branchiopoda, ostracoda
What is a ramus?
an article branch
hence biramous and uniramous appendages
What is characteristic of indirect crustacea development?
uses larval stage ( often nauplius larvae)
What deos apterygota refer to?
2 separate clades of wingless insects- also ametabolous development
What does ametabolous mean?
insect development in which there is no metamorphosis and immature stages appear very similar to the adults, except that they lack genitalia
How would you describe pterygota?
2 pairs of wings and 4 superorders
What are the 4 superorders of pterygota?
Holometabola (beetles, flies, bees, ants…),
Paraneoptera (true bugs, lice..),
Polyneoptera (grasshoppers, termites…)
Paleoptera (mayflies, dragonflies…)
Describe Holometabolous development
egg-larva-pupa-adult
Describe Hemimetabolous development
egg-nymph-adult
What are the 4 types of specialised mouthpart appendages + examples
Lapping (honeybee), Chewing (grasshopper), siphoning (butterfly), piercing (mosquito)
How many times are wings thought to have evolved in insects?
once
How are wings thought to have evolved?
de novo- not specialised appendages
Flight is a cycle of which 2 strokes?
Power stroke (down and forward) and recovery stroke (up and back)
What do adult structures develop from in holometabolous metamorphosis?
Imaginal discs
What is dipause?
a period of suspended development in an insect, other invertebrate, or mammal embryo, especially during unfavourable environmental conditions.
Give 3 factors conrtibuting to arthropod success
1- adaptations for terrestrial existance
2- Co-evolution with angiosperms
3- Eusociality
