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| − | ==Structure and Function== | + | ==[[Insect Structure and Function]]== |
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| − | ===Insect Body===
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| − |
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| − | *Covered by an exoskeleton
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| − | **Provides support and protection to the living tissues
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| − | **Acellular so is secreted by underlying epidermis
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| − | **The outer layer is called the '''epicuticle''' which is composed of proteins and covered by a waxy layer
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| − | **The inner layers are the '''endocuticle''' and '''exocuticle''' which are composed of protein and chitin
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| − |
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| − | *Body is '''metameric''' (divided into segments)
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| − |
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| − | *Divided into head, body and abdomen
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| − | **Articular membranes link segments allowing movement
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| − |
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| − | ===Insect Head===
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| − | [[Image:Insect Head and eyes.jpg|thumb|right|150px|Alan Hadley]]
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| − | [[Image:Insect Eyes.jpg|thumb|right|150px|Alan Hadley]]
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| − | [[Image:Blow fly head.jpg|thumb|right|150px|Blowfly Head Close Up - Martin Pot - Wikimedia Commons]]
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| − | *Capsule of fused plates at the anterior end of the body
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| − |
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| − | *One large pair of compound eyes
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| − | **Honeycomb like corneal facets
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| − |
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| − | *Three simple ocelli
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| − | **Dorsal to compound eyes
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| − |
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| − | *One pair of antennae
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| − |
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| − | ====Antennae====
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| − |
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| − | *Form varies amongst insecta
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| − | **E.g. long and segmented, short and squat etc.
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| − |
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| − | *[[Hair - Anatomy & Physiology|Hairs]] sometimes present
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| − |
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| − | *Aristae (bristles) sometimes present
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| − |
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| − | ====Mouthparts====
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| − |
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| − | *Modification depending on feeding method
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| − |
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| − | *Insects which suck up liquified food have an expanded sponge like labellae
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| − | **Cannot penetrate skin
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| − | **Palps are also present which are sensory structures
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| − |
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| − | *Insects which suck blood have long slender mouthparts for piercing skin
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| − | **Hypopharynx
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| − | **Mandibles
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| − | **Labrum
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| − | **Maxillae
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| − |
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| − | *Larval mouthparts are prominent
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| − | **One pair of hooks
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| − | **Cephalo-pharyngeal skeleton
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| − | **Mouthparts help identify larvae
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| − |
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| − | ===Insect Thorax===
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| − |
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| − | *Divided into three segments
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| − | **Prothorax, mesothorax and metathorax
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| − |
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| − | *Each segment has one pair of legs attached
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| − |
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| − | *One or two pairs of wings may be present on the mesothorax and metathorax
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| − |
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| − | ====Leg====
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| − |
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| − | *Leg is attached to the body by '''coxa'''
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| − |
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| − | *Trochanter
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| − |
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| − | *Femur
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| − |
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| − | *Tibia
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| − |
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| − | *Tarsus, which is composed of several segments
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| − |
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| − | *Claw
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| − |
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| − | *Usually six-segmented
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| − |
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| − | ====Wing====
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| − | [[Image:Insect Wing Venation.jpg|thumb|right|150px|Alan Hadley]]
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| − | *Insects usually posess two pairs of wings
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| − |
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| − | *Diptera have a reduced second pair of wings called '''halteres''' for balance
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| − |
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| − | *Membranous outgrowth of the integument
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| − |
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| − | *Strengthened by a network of veins comprising breathing tubes ([[Trachea - Anatomy & Physiology|trachea]]) and [[Vascular System - Anatomy & Physiology|blood vessels]]
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| − |
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| − | *The wing venation can be used for identification
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| − | **Longitudinal veins
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| − | **Cross veins
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| − | **Open cells
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| − | **Closed cells
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| − |
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| − | ===Insect Abdomen===
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| − |
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| − | *Segmented
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| − |
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| − | *Soft
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| − |
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| − | *Appendages present
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| − | **Copulatory claspers
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| − | **Ovipositor
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| − | **External genitalia
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| − |
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| − | ====Respiratory System====
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| − |
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| − | *Branching [[Trachea - Anatomy & Physiology|trachea]] strengthened by spiral thickenings in the walls
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| − |
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| − | *[[Trachea - Anatomy & Physiology|Trachea]] communicate with outside via spiracles
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| − | **Spiracles on side of body
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| − | **Chitinous openings
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| − | **Muscular control so can open and close at will
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| − | **Mounted on stigmatic plates
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| − | **Lead to trachea
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| − |
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| − | *Muscular contactions of the body wall produce respiratory movements
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| − |
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| − | *Shape of spiracles and stigmatic plates used for species identification
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| − |
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| − | ====Alimentary and Excretary System====
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| − |
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| − | *The precise shape of the gut varies between [[:Category:Arthropods|arthropods]]
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| − |
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| − | *The Alimentary canal is divided into fore, mid and hind gut
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| − |
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| − | *Foregut:
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| − | **[[Oesophagus - Anatomy & Physiology|Oesophagus]]
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| − | **[[Crop- Anatomy and Physiology|Crop]] for temporary food storage
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| − | **[[The Proventriculus - Anatomy & Physiology|Proventriculus]]
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| − | **[[The Gizzard - Anamtomy & Physiology|Gizzard]] present in insects which eat solid food
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| − | ***Muscular wall and teeth on inner surface
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| − |
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| − | *Midgut:
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| − | **Stores food
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| − | **Secretes enzymes for digestion
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| − | **Outlet for malpighian tubules (equivalent of the mammalian kidney)
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| − |
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| − | *Hindgut:
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| − | **Water resorption
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| − |
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| − | ====Circulatory System====
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| − |
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| − | *[[Heart - Anatomy & Physiology|Heart]] situated dorsally
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| − | **Valves divide [[Heart - Anatomy & Physiology|heart]] into compartments
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| − | **Valves only let blood flow forwards
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| − |
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| − | *[[The Aortic Arches - Anatomy & Physiology|Aorta]]
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| − |
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| − | *Branching [[Vascular System - Anatomy & Physiology|blood vessels]]
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| − |
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| − | *Haemocoele
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| − | **General body cavity
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| − | **Equivalent to the capillary circulation in mammals
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| − | **Contains haemolymph
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| − |
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| − | *Ostia (openings) in the [[Vascular System - Anatomy & Physiology|blood vessel]] walls allow return of blood to the heart
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| − |
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| − | ====Nervous System====
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| − |
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| − | *Small brain above the [[Oesophagus - Anatomy & Physiology|oesophagus]]
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| − |
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| − | *Chain of fused ganglia running along the floor of the abdomen and thorax
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| − | **Nerves are given off from chain
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| − |
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| − | *Complex nervous system
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| − | **Well developed visual senses
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| − |
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| − | ====Fat Body====
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| − |
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| − | *Large structure
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| − |
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| − | *Cells containing fat vacuoles
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| − |
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| − | *Lines the body cavity and internal organs
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| − |
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| − | *Equivalent to the visceral and parietal peritoneum in mammals
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| − |
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| − | *Food reservoir during hibernation or starvation periods
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| − |
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| − | ====Reproductive System====
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| − |
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| − | *Most insects have seperate sexes
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| − |
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| − | *Reproductive organs are analogous to mammals
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| − |
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| − | *Spermatheca present in females
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| − | **Accessory female sex organ
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| − | **Recepticle for spermatozoa
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| − | **Sperm remains viable for most of the female's life cycle
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| | ==Life cycles== | | ==Life cycles== |
