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Jointed-legged invertebrates

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Presentation on theme: "Jointed-legged invertebrates"— Presentation transcript:

1 Jointed-legged invertebrates
Arthropods Jointed-legged invertebrates

2 Arthropod Characteristics
Metamerism with tagmatization Chitinous exoskeleton Paired-jointed appendages Growth with ecdysis (molting) Ventral nervous system Open circulatory system Complete digestive tract Malpighian tubules for excretion

3 Evolutionary Significance
Protostomes Schizocoelous development Paired ventral nerve cord Loss of internal metamerism Increased tagmatization (specialization of segments)

4 Terrestrial Dominance
Minimize water loss Exoskeleton Respiratory system development Advanced excretory system Greater ability for movement Exoskeleton attaches strong muscles Support

5 Exoskeleton Major reason for success of this group! Provides Support
Protection Prevention of dehydration Sites for muscle attachment

6 Exoskeleton Structure
Epicuticle (outer layer) Water tight Barrier Procuticle (inner layer) Made of chitin Allows for protection Forms joints

7 Ecdysis Shedding or molting of exoskeleton New exoskeleton is soft
Tanning (sclerotization) must take place to make outer layer of procuticle hard

8 Metamorphosis Change in body form from immature (larval) stages to adult forms Reduces competition between stages for Food Living space Larval forms often occupy different habitats than the adults do

9 Taxonomy of Arthropods
4 subphyla Trilobitomorpha (all extinct) Chelicerata Crustacea Uniramia

10 Trilobitomorpha Trilobites All extinct All marine 3 sections

11 Chelicerata Class Merostomata Class Arachnida
Horseshoe crabs Water scorpions (eurypterids) Class Arachnida Spiders Mites Ticks Scorpions Class Pycnogonida (sea spiders)

12 Chelicerate Characteristics
Two-part body Opisthosoma Chelicerae (1st pair of appendages – forms feeding palps or fangs) Pedipalps (2nd pair of appendages) Cephalothorax (prosoma) Book lungs or book gills

13 Crustacea Class Malacostraca Class Branchiopoda
Shrimp, lobsters, crayfish Isopods (wood lice – roly poly) Amphipods Class Branchiopoda Fairy shrimp, brine shrimp Water fleas

14 Class Copepoda Class Cirripedia Cyclops (freshwater) Barnacles
Sacculina – parasite of crabs

15 Crustacean Characteristics
2 pairs of antennae Biramous appendages (Y-shaped) Segments are serially homologous

16 Uniramia Class Diplopoda (millipedes) Class Chilopoda (centipedes)
Class Pauropoda Class Symphyla Class Hexapoda (insects)

17 Insect Locomotion Flight Walking (3+ legs on ground at all times)
Running (Can run on 2 legs) Swimming (legs modified as paddles) Jumping (saltatory locomotion)

18 Insect Respiration & Circulation
Tracheae & spiracle system Circulation Modified open circulatory system Some vessels Primitive Heart

19 Nervous System Johnston’s organs (hearing - on antennae)
Tympanic organs (hearing – on legs or body) Compound eyes (facets – ommatidia – fused) Simple eyes (ocelli)

20 Metamorphosis Type Appearance Young called Ametabolous
larvae look like adults, just smaller instars Paurometabolous Specific number of molts Nymphs (land) Naiads (water) Holometabolous Young very different from adults Larvae

21 Economic Impact of Arthropods
Name one effect each major group has on mankind (good or bad). For insects, list 4 good things that they do and 4 bad things that they are responsible for.

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