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Animal Diversity > Insect Anatomy & Physiology > Flashcards

Insect Anatomy & Physiology Flashcards

1
Q

What are the main parts of Insects’ external anatomy?

A
  • Segmented (generally 6+3+11 segments)
  • Exoskeleton
  • Head (antennae, compound eye, mouthparts)
  • Thorax (wings, fore leg, middle leg)
  • Abdomen (spiracles, hind leg, cercus, external genitalia)
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2
Q

What is the cuticle (exoskeleton) secreted by?

A

The epidermis

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3
Q

What are the three layers of the epidermis?

A

Epicuticle (above), exocuticle (outer) and endocuticle (inner)

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4
Q

What are the two pigments/structural mechanisms that produce the diverse colours of insects?

A
  • Pigmentation is produced by the insect’s own metabolism, sequestered from a plant source or produced by microbial endosymbionts
  • Iridescence is caused by microstructures in the surface chitin causing interference at selected wavelengths (light interference)
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5
Q

What are the key structures of the insect head and what are their roles?

A
  • Gena, clypeus, labrum
  • Frons
  • Antenna (scape, pedicel and flagellum)
  • Ocelli and compound eye
  • Mandible
  • Maxilla and maxillary palp
  • Labium and labial palp
    Used for food gathering and manipulation, sensory perception and neural integration
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6
Q

Insects can be classified based on their mouthparts. What are the two main types of mouthparts found in insects?

A

Entognathous: internal mouthparts (e.g. Collembula)
Ectognathous: external moutparts (e.g. most bugs)

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7
Q

What are some of the different classifications of insect mouthparts?

A
  • Mandibulate (e.g. ants): used for manipulating and chewing good, as well as a variety of other behaviours such as defence and transport.
  • Suctorial (e.g. true bugs and butterflies/moths): obtain food by sucking up liquids
  • Mouth hooks (e.g. fly larvae)
    Insect mouthparts are highly derived i.e. multitude of functional mechanisms across insect species.
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8
Q

What are antennae used for and what are its main parts?

A
  • Scape > pedicel > flagellum
  • Sensory structures: touch, vibration, chemicals
  • Paired and segmented, often reduced or absent in some larval stages
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9
Q

What are the three segments of the thorax?

A
  • Prothorax
  • Mesothorax
  • Metathorax
    One pair of legs per segment, wings on the mesothorax and metathorax
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10
Q

What are the three pairs of legs called, and what are their main parts?

A
  • Forelegs, midlegs and hindlegs
  • Coxa > trochanter > femur > tibia (articulated spines) > tarsus > pretarsus > claws
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11
Q

What are some of the names given to legs based on their function?

A
  • Cursorial (to run)
  • Raptorial (to seize prey e.g. Mantis)
  • Saltatorial (to jump e.g. cricket)
  • Natatorial (to swim e.g. Water Boatmen)
  • Fossorial (to dig)
  • Prehensile (to grasp e.g. knits)
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12
Q

When are the wings fully developed in insects?

A

In adult stage (imago)
- All winged insects share the same ‘ground plan’ of three zones and eight wing veins, useful for systematic biology

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13
Q

What are the two types of flight that have evolved in insects?

A
  • Direct flight - muscles directly attached to wings (primitive flight - order Odonata)
  • Indirect flight: Muscles attached to cuticle, asynchronous muscles (modern flight, most other insects).
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14
Q

What are some of the different kinds of wings?

A
  • Orthoptera (straight wings)
  • Coleoptera (shield wings)
  • Strepsiptera (turning wings)
  • Hemiptera (half wings)
  • Diptera (two wings)
  • Lepidoptera (beautiful wings)
  • Hymenoptera (membrane wings)
  • Thysanoptera (tassel wings)
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15
Q

How many segments does the abdomen usually have and what organs are housed here?

A
  • Variable number of segments (6+)
  • Reproductive, respiratory and digestive organs
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16
Q

What structures are found in the terminal region of insects?

A
  • Ovipositer (females)
  • Cerci: sensory organs, defence/predation (rare)
17
Q

What kind of respiratory system do insects have and how does it function?

A
  • Insects have an open circulatory system with no blood vessels and no specialised oxygen carrier cells.
  • The insect body cavity - the heamocoel is filled with heamolymph
  • Gaseous exchange between the air and heamolymph achieved via tracheal system
18
Q

What is the tracheal system and what are its components? What limitations does this type of respiratory system have on insects?

A
  • Made up of spiracles (openings of the tracheal system)
  • Gas exchange occurs via air-filled trachea that sub-divide into a blind end (doesn’t connect to anything), thin-walled tracheoles filled with fluid
  • Passive respiration systems like this put a constraint on insect size
19
Q

How does the tracheal system differ in aquatic insects?

A

Most aquatic insects have a closed tracheal system, with gills instead of spiracles

20
Q

What are the three main sections of the insect digestive system and what are their components?

A
  • Foregut (pharynx, oesophagus, crop, salivary gland, proventriculus)
  • Midgut (ceaca, Malpighian tubes, ventriculus)
  • Hindgut (ileum, colon, rectum, anus)
21
Q

What part of digestion occurs in the foregut?

A
  • Ingestion, grinding, lubrication, storage, transfer to midgut
  • Paired labial/salivary glads to produce saliva
  • Saliva adjusts the PH of the food
22
Q

What function does the midgut provide in digestion, and how does it carry out said function(s)?

A
  • Production of digestive enzymes (primarily in caeca), grinding, absorption of nutrients (primarily in ventriculus)
  • Two distinct areas: ventriculus and caeca
  • The caeca are seperated from the food by a thin sheath called the peritrophic membrane
23
Q

What part of digestion occurs in the hindgut?

A
  • Absorption of water/ions, excretion
  • Malpighian tubules collect waste from the haemolymph and excrete it into the hind gut
  • The rectum reabsorbs water
24
Q

What kind of muscles do insects have and how do they carry out locomotion?

A
  • Only striated muscles (i.e. with sarcomeres, unlike smooth muscles)
  • Muscle Fibers: Insects have muscles made up of many cells. These cells share a common outer membrane called the sarcolemma. This membrane covers and protects the muscle fibers.
  • Oxygen Intake: The sarcolemma (muscle cell membrane) is folded inward, creating tiny tunnels called tracheoles. These tracheoles allow oxygen to enter the muscle fibers, providing them with the oxygen they need for energy during movement.
25
Q

What are the two different types of muscles and their roles?

A
  • Synchronous: one contraction per nerve impulse
  • Asynchronous muscles: many contractions per impulse (used for high-frequency movements such as indirect flight)
26
Q

How do insects commonly move?

A
  • By alternating tripod gait
  • Stable at low speeds - unstable at high speeds or when carrying a load
27
Q

How is the insect nervous system divided up?

A
  • The central nervous system is the principal division of the nervous system
  • It consists of a series of ganglia
  • Insects have one pair of ganglia per segment
  • The peripheral nervous system consists of all the motor neurons that radiate to the muscles and nerves
28
Q

What are the main components of the insect endocrine system and what are their function(s)?

A
  • Neurosecretory cells: produce most of the insect hormones (except juv. hormone and acdysteroids)
  • Corpus allatum: produce juvenile hormone (metamorphosis and reproduction)
  • Prothoracic glands: store and secrete ecdysone (moulting hormone)
  • Corpus cardiacum: stores and releases hormones from the neurosecretory cells
29
Q

What are the main structures in the female reproductive system?

A
  • Paired ovaries release mature oocytes (eggs) via the calyces
  • Lateral oviducts combine, and the eggs pass through the gonopore into the genital chamber, which serves as a copulatory pouch during mating
  • Sperm is often stored in the spermatheca and released as the eggs pass by
  • Accessory glads produce extra secretions (e.g. cement for ootheca)
30
Q

What are the main structures in the male reproductive system?

A
  • A pair of testes open into the vas deferens
  • The vas deferens empty into a storage vesivle
  • The accessory glands provides the spermatophore (package surrounding the spermatozoa) and help nourish the sperm
  • The ejaculatory duct empties to the gonopore
  • Males have an aedeagus (intromittent organ or penis)
31
Q

What is sperm competition?

A
  • Multiple mating is a common occurrence in insects
  • Combination of multiple matings and sperm storage has resulted in “sperm competition” either by:
  • Sperm displacement: where a male pushed other males sperm to the back of the spermetheca (last-in-first-out)
  • Sperm removal: where a male removes other sperm prior to depositing his own
  • Direct sperm competition within the spermatheca

Animal Diversity (9 decks)

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