16-Insecta.pdf - Todayu2019s Contents u2022 Review of the...

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Today’s Contents Review of the last lecture on Crustacea • Hexapoda 1
2 Brushup of the last lecture
ARTHROPODA 2 SUBPHYLUM CRUSTACEA BIOL1309 Evolutionary Diversity
SUBPHYLUM CRUSTACEA General Characteristics: The Crustacea are a large group (~52,000 spp. described) of ecdysozoans whose members are primarily aquatic (they moult, or undergo ecdysis as they grow). Most are marine, some freshwater, but only a few have radiated into terrestrial habitats. Diversity of crustacean anatomy is huge! Typically comprise 3 body segments: head, thorax and abdomen . 4
Main Characteristics of Crustacea Crustacea possess 2 pairs of antennae (which are jointed in some species, e.g. in lobsters) – this feature separates them from the phylum Chelicerata (which have 1 pair of antennae). Crustacea have biramous appendages, which separates them from the Insecta (which have uniramous appendages). 5 In many crustaceans, the cuticle is thickened and strengthened with deposits of calcium carbonate, i.e. the cuticle is calcified . Alaskan king crab
Crustacea: body organization of a shrimp Body is divided into functional units (= tagmata): head, thorax – which are fused to form the cephalothorax , covered by the carapace , and abdomen 6
Comparing the structure of different types of appendages Phyllopodous Stenopodous Generalised function: locomotion, feeding, respiration, sensation, etc. More specialised functions, fewer
Crustacean Classes 1. Class Branchiopoda 2. Class Ostracoda 3. Class Copepoda 4. Class Branchiura 5. Infraclass Cirripedia (in Thecostraca) 6. Class Malacostraca Malacostraca contains ~75% of known crustacean species, including most that are of direct economic benefit to humans, e.g. shrimps and crabs. Tree of Life
9 BRANCHIOPODA Anostraca Notostraca Cladocera OSTRACODA
10 COPEPODA BRANCHIURA CIRRIPEDIA
11 They are just attached on the surface and doing suspension feeding
12 MALACOSTRACA Stomatopoda Isopoda Amphipoda Euphausiacea Decapoda
Recapitulation: trends in evolution of crustacean appendages From phyllopodous to stenopodous From biramous to (predominately) uniramous From many to few From generalism to specialism From similarity to diversity (between species & within individuals) 13
14 e.g., NOTOSTRACA e.g., DECAPODA Similarity Diversity to Similar shaped appendages Specialized appendages Similar morphology Huge variation
PHYLUM ARTHROPODA SUBPHYLUM HEXAPODA BIOL1309 Evolutionary Diversity Moriaki Yasuhara Photo by C. Yau: Common hedge blue butterfly
THE ECDYSOZOA 16 Hexapoda
17 SUBPHYLUM HEXAPODA From Greek meaning ‘six legs’. ! Composed of Class Insecta (insects) and Class Entognatha .
18 1. Class Entognatha ! Formerly “Wingless insects” are grouped as the class Apterygota within Insecta. ! But, recent research revealed Apterygota is paraphyletic. ! Then some of “Wingless insects” are grouped as the class Entognatha (outside of Insecta) under Hexapoda.

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