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44 Cards in this Set
- Front
- Back
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Principal Characters of
the Phylum Arthropoda |
1. Segmented body
2. Paired segmented appendages 3 Bilateral symmentry 3. Bilateral symmentry 4. Chitinous exoskeleton 5. Tubular alimentary canal (mouth –anus) 6. Open circulatory system 7. Hemocoel or blood cavity |
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Principal Characters of
the Phylum Arthropoda (pt 2) |
8. Ventral central nervous system
9 Striated skeletal muscles 9. Striated skeletal muscles 10.Excretion by Malpighian tubules 11. Respiration via gills or tracheae and spiracles 12.Sexes are usually separate |
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The phylum arthropoda has been
divided into four subphyla based on structural differences of their mouthparts |
"Trilobita
"Chelicerata "Crustacea "Atelocerata (Mandibulata) |
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!Subphylum: Chelicerata
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"Class: Merostomata (horsehoe crabs)
"Class: Arachnida: (Arachnids) |
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"Class: Arachnida: (Arachnids)
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•Order: Scorpiones (scorpions)
•Order: Opiliones (daddy-long-legs) •Order: Acari (mites & ticks) •Order: Araneae (spiders) |
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!Subphylum: Crustacea (crustaceans)
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"Class: Malacostraca (one of ten)
•Order: Decapoda (lobsters, crayfish, crabs and shrimp) •Order: Isopoda (sowbugs, pillbugs, roly-polys) •Order: Amphipoda: (beach fleas) |
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Subphylum: Chelicerata (Extant)
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!no antennae
!most have 4 pairs of walking legs, 1 pair of leg-like pedipalps !2 or 3 segmented mouthparts with opposable fangs |
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Class: Merostomata (horseshoe crabs)
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! 4 known species
" 1 on North American Atlantic coast " 3 on Pacific and Indian Ocean coasts of India, Japan, & Indonesia " Spine or sword-like tail Ca 300 MY Old |
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Isopoda:
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-sowbugs, pillbugs, roly-
polys), 26,000 species, many marine forms, dorsoventrally flattened |
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order Amphipoda:
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subphylum crustacea
beach fleas, scuds, laterally flattened, marine and freshwater forms. |
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Decapoda
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-Crayfish, lobsters, crabs, etc.
-Ten legs, most edible arthropods: lobsters, crayfish, crabs and shrimp) |
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Spiders
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!Approximately 35,000 species
worldwide !Approximately 3,000 species in North America !All are predators |
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Spiders (features)
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! Two body regions
! Eight legs ! Chelicerae ! Pedipalps ! Often eight eyes ! No antennae or wings ! Immatures often resemble adults except in size & sometimes color Legs all attached to the cephalothorax |
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Subphylum: Atelocerata (Mandibulata)
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!Divided into 2 superclasses
"Myriapoda (myri = many; poda = feet) "Hexapoda(hexa = 6; poda = feet) !all have "one pair of antennae "one part (simple) mandibles "much variation in mandible form "2 or 3 body functional body regions (tagma) |
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Benefits of an exoskeleton
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high strength to weight ratio of hollow tubes
protects against water loss (lipid layer) pathogens predators parasites / parasitoids flexibility |
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Drawbacks of an exoskeleton
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Molting
most insects molt between 4 and 11 times between egg and adult stages Weight to provide enough structural strength the weight of a large exoskeleton (our size) would restrict movement largest arthropods are all aquatic |
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Digestive & Excretory systems
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Foregut (stomodeum)
lined with exoskeleton (intima) Midgut (mesenteron) endodermal tissue Hindgut (proctodeum) lined with exoskeleton (intima) |
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Foregut
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–lined with exoskeleton
(intima) non-permeable Esophagus (tube from mouth to crop) Crop (food storage) Proventriculus (valve or grinding structure) |
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Midgut
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permeable
Gastric caecae (nutrient passage to hemolymph) Ventriculus (nutrient passage to hemolymph) |
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Developmental origin of the alimentary canal?
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foregut and hindgut=ectoderm
midgut and Malpighian tubules=mesoderm |
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Functions of foregut, midgut, and hindgut
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FOREGUT: mech. breakdown, food processing, storage (crop)
MIDGUT: digestions, absorption (enzymes) HINDGUT: excretion, sybiont storage, reabsorption, H2O regulation |
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Hindgut
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Lined with exoskeleton (intima) mostly non-permeable
Malphigian tubules (kidney functions) Intestine (waste to rectum) Rectum (waste elimination, water and sugar recovery) |
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Fat body
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Makes up to 65% of body weight in some insects
Functions synthesis and storage of energy as fat •fat content is highest in reproductively active females and individuals in the migratory phase •mainly triglycerides storage site for sugars •sugars in hemolymph are converted to glycogen for storage in the fat body •converted to trehalose and released back into the hemolymph when needed |
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Dorsal vessel
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The primary hemolymph flow pump
*Suspended under dorsal body surface by the alary muscles and dorsal diaphragm *Tube running from posterior end of the abdomen to the head *Ostia = lateral openings on the posterior end to allow hemolymph to enter *Peristaltic muscle contractions close ostia and force hemolymph out the anterior end into the head |
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Accessory pumps
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Move hemolymph in to and out of
appendages Consist of a “bellows” formed by muscles at the base of the appendage Normal movement of the appendage makes these pumps function Most appendages divided by a septum |
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Hemolymph (insect blood)
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Functions like our blood EXCEPTit does not transport respiratory gases (O2& CO2)
stores: water, sugars, salts carries: nutrients, hormones, metabolic wastes Contains a variety of blood cells Colors clear, yellow, white, or green fluid usually not red (no hemoglobin) 5 to 40% of insect’s live weight low % in hard-bodied insects (ant) high % in soft-bodied insects (caterpillar) |
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Functions of Hemolymph
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Hydraulic functions
Used to apply pressure to ecdysial suture at molting Movement of pseudosegments in tarsi, antennae, cerci Movement of caterpillars & other soft-bodied immatures (grubs, maggots, etc.) |
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Functions of Hemolymph
(pt 2) |
Thermoregulation
Storage & transport of nutrients, water, metabolic wastes,hormones NOT important in moving respiratory gasses (no hemoglobin) |
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Spiracles
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Openings through the body wall
2 pairs on thorax 1 pair on most abdominal segments Opening is triggered by high CO2level inside the system Closure prevents H2O loss |
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Trachea
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Network of gas-filled tubes
carry respiratory gasses throughout body Largest diameter at the spiracles Largest have spiral internal ridges for strength (taenidia) |
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Internal components of integuement
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Apophysis- internal spike -dimple
Phragma- deep ridge- seam Internal ridge- shallow ridge - seam |
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External structures
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Spine
non-movable projection of exoskeleton Spur movable projection of exoskeleton Seta (setae is pleural) hair-like, sensory projection of exoskeleton |
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Molting
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Apolysis
separation of old cuticle from epidermis Ecdysis shedding of old cuticle formation of new cuticle |
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Apterygota
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No wing
Silverfish Bristletail (Jumping Bristletails) |
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Pterygota
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Paleoptera (old winged)
•wings can’t be held flat over the body at rest Neoptera (new winged) •wings are folded flat over back at rest |
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Light reception
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"compound eyes
"ocelli "stemmata |
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"compound eyes
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Single pair in most adult & immature
insects "cave and soil dwellers are exceptions !Each compound eye is made up of a group of individual light receptors called ommatidia |
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"ocelli
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!Mainly in day-active insects
!Usually have 3 !Structurally these can not form an image, and only perceive changes in light level "Trigger escape response !In some they perceive polarization angle of light for navigation |
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"stemmata
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!Structurally like ommitidia
!Each can form an image BUT since they are not grouped together and there are only a few they are not good image forming eyes. |
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Antennae
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!Structure (3 segments)
"scape - first (base) segment "pedicel - second segment "flagellum- third segment (pseudosegments) |
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Antennae
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filiform (long, thin,
all segments similar) plumose (feathery) Aristate (last segment of 3 finger like with a bristile) setaceous (hair like) lamellate (elbowed, with layers that can open and close) serrate (saw toothed) pectinate, (comb like) |
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Legs
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!Almost all insects have 3 pairs, 1 each on the prothorax, mesothorax,
metathorax "a few, like maggots, have none !All insect legs have 7 primary parts "coxa, trochanter, femur, tibia, tarsus, pretarsus, claws |
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Abdominal structures
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!Cerci
!Median caudal filament !External reproductive structures "ovipositor in females "claspers in males |
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Thoracic skeletal muscles
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Four main groups
Within a segment •dorsal longitudinal muscles •ventral longitudinal muscles •tergo-sternal muscles Between segments •oblique intersegmental muscles |
