EXAM 1 Flashcards
Dr Stout/Dr Lord classes
5 characteristics that differentiate arthropods
Bilateral symmetry Cephalization Exoskeleton with chitin Tagmosis True coelom
Name two characteristics that distinguishes insects from non-insects arthropods.
Most insects have wings and undergo metamorphosis.
What is cephalization and how does the insect head exemplifies this evolutionary trend in animal body plans?
Cephalization is the concentration of nervous and sensory organs into the head. Insects posses a variety of sensory organs in the head such as compound eyes, ocelli, antennae, maxillary palps, etc.
What are the five major orders of insects?
1 - Coleoptera 2 - Hymenoptera 3 - Diptera 4 - Lepidoptera 5 - Hemiptera
What features of insects contribute to success and diversity?
Flight Metamorphosis, which reduces competition between immatures and adults. Coevolutionary relationships with plants Complete metamorphosis Highly organized sensory and neural systems Sexual selection Small size Short generation times
Why are insects important? Positive Roles
- Food for insectivorous animals
- Maintenance of animal and plant communities via herbivory, parasitism, disease transmission
- Basic biological models
- Nutrient recycling (wood, litter degradation), soil creation, etc.
- Source of food, textiles, and other products
- Source of novel chemicals
Why are insects important? Negative Roles
- Pests of crops and livestock
- Pests of structures
- Vectors of diseases
What is poikilothermy?
Body temperature varies according to the environment.
Three basic types of development
- Ametabolous: develop to adulthood with little change in body form except sexual maturation (Apterygota)
- Hemimetabolous: gradual change in body form, wings develop gradually, no pupal stage. Immatures = nymphs
- Holometabolous: complete metamorphosis, pupal stage, abrupt change in body form. Immatures = larvae
Exoskeleton limits size of insects?
Recent studies suggest that the respiratory systems in an important limiting factor on insect size. Particularly, insufficient space for tracheae in legs of insects.
Epicuticle layers and function.
Cement layer
Wax layer
Superficial layer
Deter predators. Retain water. Olfactory cue. Patterns for mimicry or camouflage.
Wax production and transportation.
Wax is produced by dermal glands in epidermis, secreted to epicuticle via pore canals and wax canals.
Procuticle layers, function, and sclerotization.
Procuticle is formed by exocuticle and endocuticle. This layer provides support and its composed of chitin. Exocuticle is the layer where sclerotization occurs.
How does procuticle provide structure?
Chitin molecules group into microfibrils. Microfibrils embedded and attached to protein matrix. Microfibrils lay down in sheets arranged in parallel. Each successive sheet rotates slightly.
How does the strength of cuticle and sclerotization (tanning) occur?
Hydrogen bonding of adjacent chitin chains provides strength. Sclerotization in exocuticle provides additional strength, resulting in hardening, darkening, and water insolubility.
What is resilin? Where is resilin found?
Resilin is a rubber-like protein that acts as a mechanical spring. It can be found in soft/elastic parts of cuticle.
Three specialized structures associated with integument?
Setae (macrotrichia, trichoid sensilla, hairs)
-Hollow extensions of cuticle, multicellular
-Trichogen and tormogen cells associated with setae
-Sensory setae involved in sensing environment
-The scales in Lepidopterans are specialized setae
Spines: multicellular, undifferentiated epidermal cells
Microtrichia (minute hair-like structures)
How is color produced in insects?
- Color produced by interaction of light with cuticle.
- Physical (structural) colors- light scattering, interference, diffraction. Result of, for example, microfibril orientation in cuticle.
- Pigmentary colors – absorption of visible light by chemicals. Pigments in cuticle, epidermis.
- Sclerotization also results in darkening
What is apodeme and apophysis?
Apodemes are internal inflections of the cuticle which provide rigidity and sites for muscle attachment. The term apophysis is also used to indicate an elongated apodeme. Apophyses may fuse to form endoskeletal structures. Examples of endoskeletal structures are the tentorium in the head and the pro-, meso-, and metendosterna in the thorax.
Segmentation plates
Tergum (terga) = dorsal plate
Sternum (sterna) = ventral plate
Pleuron (pleura) = side plates
