ARTHROPODS SUBPHYLA: TRILOBITA, CRUSTACEA, CHELICERATA, AND UNIRAMIA.
Ch. 15 Notes The Arthropods: Part 2. Phylum Arthropoda Review 5 Subphyla: 1.Trilobitomorpha –...
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Transcript of Ch. 15 Notes The Arthropods: Part 2. Phylum Arthropoda Review 5 Subphyla: 1.Trilobitomorpha –...
Ch. 15 Notes
The Arthropods: Part 2
Phylum Arthropoda Review
5 Subphyla:1. Trilobitomorpha – extinct – trilobites– Marine– Cambrian-Carboniferous time period
2. Chelicerata – spiders, mites, ticks, horseshoe crabs, sea spiders, scorpions
3. Crustacea – ‘hard shelled’ – crayfish, shrimp, lobster, crabs, water fleas, barnacles
4. Myriapoda – millipedes & centipedes5. Hexapoda – ‘six legs’ – insects & their relatives
Subphylum Myriapoda
• Class Diplopoda – two-fold foot– Millipedes – 11-100 trunk segments– Two pairs of appendages on each trunk segment– Actually the fusion of two segments
• 2 ostia – opening @ end of oviduct• 2 ganglia• 2 tracheal trunks – part of circulatory system –
transports O2
– Glands produce Hydrogen Cyanide to repel other animals
– Round bodies in cross section
Subphylum Myriapoda
• Class Chilopoda – lip foot– Centipedes– Nocturnal– Flattened bodies in cross section– Poison claws– Only 1 pair of appendages per segment– Add legs and segments with each molt
Subphylum: Hexopoda
• Includes Insects & their relatives• Body divided into 3 Tagmata: – Head, thorax, abdomen
• 5 pairs of head appendages• 3 pairs of legs on the thorax (6 legs)
Class Insecta
Habitat:• terrestrial, aquatic, & aerial– Insects are the most successful land animals
Class Insecta
Locomotion• Flight is the most important form of locomotion– Insects were 1st animals to fly– Must be able to thermoregulate
• Maintain body temperatures different from environment
• Walk/Run• Jump• Swim
Class Insecta
Thermoregulation• Ectotherms– Most insects– Rely on sun or warm surface
• Heterotherms– Rely on metabolic heat– Shivering Thermogenesis• Generate heat by rapid contraction of flight muscles
Class Insecta
Digestive Tract• Long & Straight• 3 Regions
– Foregut• Musculary pharynx/oral cavity• Used for sucking fluids• Crop (storage)• Gizzard (regulates movement to midgut; grinds food)
– Midgut• Surface for digestion & absorption
– Hindgut• The Intestine• Reabsorption of Water
Class Insecta
Excretory System• Nitrogenous wastes
converted to uric acid– conserves water– energetically expensive
• Malpighian tubules transport uric acid to the digestive tract
Class Insecta
Respiration – a Simple System• Have trachea- chitin lined tubes– Open to outside through spiracles – Oxygen diffuses from trachea to body tissues
• Aquatic insects– Spiracles are nonfunctional – Gasses diffuse across body wall
• Blood is not important for gas exchange in insects
Class Insecta
Do insects have blood?
Circulatory System• Open Circulatory System• Less developed blood vessels• Blood distributes nutrients, hormones, &
wastes
Class InsectaNervous Communication• Pheromones – Chemicals
released by one individual that affects the behavior of another– Chemoreceptors – pores
through which chemicals diffuse • Feeding• Selection of egg laying sites• Mate location• Social organization
Class Insecta
Nervous Communication Continued…• Hormones regulate
– Ecdysis– Metamorphosis
• Eclosion – the emergence of an insect from a cocoon, chrysalis, or puparium– Cocoon- Protective case enclosing the
pupal stage, made of silk– Chrysalis- Last larval exoskeleton
maintained during the pupal stage– Puparium- an outer covering that
protects the pupae of some flies
Class Insecta
Nervous Communication Continued…
• Insects are capable of memory• Johnston’s organs – the base of
the antennae of most insects– Long setae that vibrate when certain
frequencies of sound strike them – Mosquitoes and fruit flies hear using
the Johnston's organ
Class Insecta
Nervous Communication Continued…• Sense organs– Mechanoreceptors – perceive physical
displacement of the body or body parts– Setae – distributed over mouthparts, antennae,
legs• Touch, air movements, and vibrations move setae
– Stretch Receptors – located @ joints & muscles• Monitor position and posture
Class Insecta
Nervous Communication Continued…
Sound• Tympanic organs– Consist of a thin, membrane
covering a large air sac– Air sac acts as a resonating
chamber– Sensory cells under membrane
to detect pressure waves
Class Insecta
Nervous Communication Continued…Sight• All insects are capable of detecting light• Compound Eyes
– Well developed eyes– Not a very good image– Good at detecting movement– Sometimes can detect polarized light– Made up of 1000’s of Ommatidia
• Each is a lens w/ a crystaline cone• Cells have a rhabdom light collecting area
– Converts light energy into nerve impulses
• Ocelli – simple eyes– Hundreds of photo receptors
Class Insecta
Reproduction• Adaptations for land– Resistant eggs– External genitalia– Behavioral mechanisms
that bring males and females together at appropriate times• Pheromones• Visual signals• Auditory signals
Class Insecta
Relationships• Many insects are social– They live in colonies– Each kind of individual in an insect colony is called
a caste• Many are beneficial to humans• Few are parasites or transmit diseases to
humans or plants