BIO2231 - Arthropoda I

Question 1

<p><strong><span>What is Metamerism?</span></strong></p>

<p>5 points.</p>

Answer 1

<p><span>Segmentation</span></p>

<ul><li>A form of compartmentalisation </li><li>Serial repetition of segments </li><li>Can involve internal/external structures </li><li>Linked to increased mobility </li><li>Allows complexity and specialised functions</li></ul>

<p><span>_{BIO2231 6aa}</span></p>

Question 2

<p><strong><span>What is characteristic of Ecdysozoa</span></strong></p>

<p>6 points.</p>

Answer 2

<p><span>Cuticle with molting</span></p>

<div>Primarily <strong>Arthropoda, </strong>also Nematoda</div>

<div></div>

<ul> <li>Hard cuticle (three-layered exoskeleton of organic material) </li> <li>Ecdysis (moulting) & ecdysteroids (hormones) </li> <li>No locomotory cilia </li> <li>No primary larva </li> <li>Internal fertilization with amoeboid sperm </li> <li><strong>Primarily defined by molecular phylogeny!</strong></li></ul>

<p><span>_{BIO2231 6ab}</span></p>

Question 3

<p><strong><span>What does Arthropoda consist of?</span></strong></p>

<p>9 points.</p>

Answer 3

<p><span>The highly versatile body plan</span></p>

<ul><li>Spiders</li><li>Scorpions</li><li>Ticks</li><li>Mites</li><li>Crustaceans</li><li>Millipeads</li><li>Centipeads</li><li>Insects</li><li>And smaller phyla</li></ul>

<p><span>_{BIO2231 6ac}</span></p>

Question 4

<p><span>Major characteristics</span></p>

<p><strong><span>Arthropoda</span></strong></p>

<p>7 points.</p>

Answer 4

<ul> <li>Bilaterally symmetrical and triploblastic</li> <li>Segmentation-with regional specialisation (tagmosis)</li> <li>Paired articulated appendages surrounded by chitinous cuticle</li> <li>Growth via molting: ecdysis</li> <li>Usually present - paired compound eyes</li> <li>Coelom: reduced to haemocoel</li> <li>Muscles striated in segmented bands </li></ul>

<div></div>

<div><strong>THE BIGGEST PHYLUM!</strong></div>

<p><span>_{BIO2231 6ad}</span></p>

Question 5

<p><span>Phylum Arthropoda</span></p>

<p><strong><span>Possible reasons for success?</span></strong></p>

<p>7 points.</p>

Answer 5

<ol> <li>Cuticle (exoskeleton)</li> <li>Segmentation and tagmata</li> <li>Jointed appendages</li> <li>Air piped directly to cells</li> <li>Cephalization & highly developed sensory systems</li> <li>Complex behaviour patterns</li> <li>Reduced competition through metamorphosis</li></ol>

<p><span>_{BIO2231 6ae}</span></p>

Question 6

<p><span>Describe</span></p>

<p><strong><span>Cuticle (exoskeleton)</span></strong></p>

<p>4 points.</p>

Answer 6

<p><span>Chitin and protein</span></p>

<div>FUNCTIONS: </div>

<ul> <li>Protective but flexible </li> <li>Chemical barrier </li> <li>Muscle attachment </li> <li>Dessication prevention (important role for terrestrial arthropods)</li></ul>

<p><span>_{BIO2231 6af}</span></p>

Question 7

<p><strong><span>What is ecdysis?</span></strong></p>

<p>8 points.</p>

Answer 7

<p><span>Moulting of the cuticle.</span></p>

<ul> <li>Large metabolic investment</li> <li>More than discarding old cuticle</li> <li>Recycle:</li> <ul> <li>chitinases breakdown the chitin</li> <li>proteinases attack the proteins to regenerate amino acid subunits</li> <li>calcium salts reabsorbed</li> <li>Help build the new cuticle</li> </ul> <li>Rebuild (part of) the body</li></ul>

<p><span>_{BIO2231 6ag}</span></p>

Question 8

<p><span>Explain construction:</span></p>

<p><strong><span>Cuticle (exoskeleton)</span></strong></p>

<p>8 points.</p>

Answer 8

<ul> <li>Strength - Mix of chitin and cuticular proteins</li> <li>Mix is solidified in the <strong>PROCUTICLE </strong>by</li> <ul> <li>cross linking (Chelicerates and Insects)</li> <li>embedding calcium salts (Crustaceans)</li> </ul> <li>Chemical Barrier - created <strong>EPICUTICLE</strong></li> <ul> <li>complex mix of proteins and waxes</li> <li>waterproofing</li> <li>adaptation for terrestrial habitat</li> </ul></ul>

<p><span>_{BIO2231 6ah}</span></p>

Question 9

<p><strong><span>What is a Tagma?</span></strong></p>

<p>2 points.</p>

Answer 9

<p><span>Functional unit of segmentation</span></p>

<div>Plural = Tagmata</div>

<div></div>

<ul> <li>Fusion of several segments</li> <li>Usually dedicated to a particular function.</li></ul>

<p><span>_{BIO2231 6ai}</span></p>

Question 10

<p><span>What is:</span></p>

<p><strong><span>Tagmatizatino</span></strong></p>

<p>2 points.</p>

Answer 10

<p><span>Specialisation of body region for feeding moving and sensing</span></p>

<div>Example: Insects </div>

<ul> <li>Head, throax, abdomen</li></ul>

<div>Example: crustaceans</div>

<ul> <li>head and thorax combined form a cephalothorax</li></ul>

<p><span>_{BIO2231 6aj}</span></p>

Question 11

<p><strong><span>Jointed appendages</span></strong></p>

<p>4 points.</p>

Answer 11

<ul> <li>Muscles and movement: increased precision</li> <li>Complex articulation of joints</li> <li>Muscular insertions allow highly coordinated movement</li> <li>Branching of appendages is an important taxonomic feature</li></ul>

<p><span>_{BIO2231 6ak}</span></p>

Question 12

<p><strong><span>How is air piped directly to cells?</span></strong></p>

<p>5 points.</p>

Answer 12

<div>Terrestrial insect (grasshopper)</div>

<ul> <li>Small, closeable spiracles</li> <li>Highly branched internally</li></ul>

<div>Aquatic insect (damselfly)</div>

<ul> <li>External gills, no spiracles</li> <li>Highly branched externally</li></ul>

<div>Spiders</div>

<ul> <li>Book lungs</li></ul>

<p><span>_{BIO2231 6al}</span></p>

Question 13

<p><strong><span>What is the impact of air piped directly to cells?</span></strong></p>

<p>3 points.</p>

Answer 13

<ul><li>Significant for colonisation of land </li><li>Implication of speed of delivery </li><li>Aquatic species breathe mainly by gills (modified appendages)</li></ul>

<p><span>_{BIO2231 6am}</span></p>

Question 14

<p><span>Describe</span></p>

<p><strong><span>Cephalisation</span></strong></p>

<p>5 points.</p>

Answer 14

<ul><li>Concentration of sense organs to the anterior end of the body i.e. head and brain </li><li>Clearly defined head </li><li>Concentration of ganglia = brain </li><li>Sensory structures </li><li>Appendages are adapted as antennae and mouthparts</li></ul>

<p><span>_{BIO2231 6an}</span></p>

Question 15

<p><span>Major characteristics</span></p>

<p><strong><span>Cephalisation</span></strong></p>

<p>4 points.</p>

Answer 15

<ul> <li>Sensory systems are highly developed and concentrated on head</li> <li>Compound eyes</li> <li>Antennae & Palps</li> <ul> <li>Tactile and chemosensitive bristles (setae)</li> </ul></ul>

<p><span>_{BIO2231 6ao}</span></p>

Question 16

<p><span>Major characteristics</span></p>

<p><strong><span>Complex behaviour patterns</span></strong></p>

<p>8 points.</p>

Answer 16

<ul> <li>Responsive to external and internal stimuli</li> <li>Simple responses</li> <ul> <li>Light and odours</li> </ul> <li>Complex responses</li> <ul> <li>Innate and learned</li> <li>Pheromones</li> <li>Sound production</li> <li>Social behaviou</li> </ul></ul>

<p><span>_{BIO2231 6ap}</span></p>

Question 17

<p><span>What is the impact of:</span></p>

<p><strong><span>Metamorphosis</span></strong></p>

<p>2 points.</p>

Answer 17

<ul><li>Reduces competition between life stages </li><li>Can separate energy gathering and dispersal stages</li></ul>

<p><span>_{BIO2231 6aq}</span></p>

Question 18

<p><span>Describe</span></p>

<p><strong><span>Sub-Phylum Trilobita</span></strong></p>

<div>5 points.</div>

Answer 18

<ul> <li>Typical trilobed body in cross-section</li> <li>Abundant in Cambrian</li> <li>Extinct ± 250 MYA (Permian extinction event)</li> <li>Scavengers (??)</li> <li>Body structure</li> <ul> <li>Three tagmata (Head, Trunk &Pygidium)</li> <li>One pair of antennae </li> <li>Highly developed compound eyes </li> <li>Many similar segments </li> <li>Biramous appendages w. gills</li> </ul></ul>

<p><span>_{BIO2231 6ar}</span></p>

Question 19

<p><span>Describe</span></p>

<p><strong><span>Subphylum Chelicerata</span></strong></p>

Answer 19

E.g. Class Arachnida (spiders, scorpions, mites) <br></br>E.g. Class Merostomata (Horseshoe crabs)<p style="text-align:right;"><span>_{BIO2231 6as}</span></p>

Question 20

<p><strong><span>Subphylum Myriapoda</span></strong></p>

Answer 20

E.g. Class Chilopoda (Centipedes) <br></br>E.g. Class Diplopoda (Millipedes)<p style="text-align:right;"><span>_{BIO2231 6at}</span></p>

Question 21

<p><strong><span>Subphylum Crustacea</span></strong></p>

Answer 21

E.g Class Branchiopoda (tadpole shrimp, water fleas) <br></br>E.g. Class Malostraca (crabs, shrimp, crayfish, amphipods, slaters)<p style="text-align:right;"><span>_{BIO2231 6au}</span></p>

Question 22

<p><strong><span>Subphylum Hexapoda</span></strong></p>

<p>4 points.</p>

Answer 22

<ul> <li>E.g. Class Insecta</li> <ul> <li>Extremely diverse</li> <li>A major biological 'success story'</li> <li>Terrestrial</li> </ul></ul>

<p><span>_{BIO2231 6av}</span></p>