Respiratory system of Annelids and Arthropods (short expn)

INVERTEBRATES RESPIRATION

Structure and Function of Organism

ANNELIDS

Annelids

• Annelids exchange oxygen and carbon dioxide with the environment through their body surfaces; most lack gills or lungs.

• Much of their oxygen supply reaches the different parts of their bodies through their blood vessels.

• Parapodia and gills serve for gaseous exchange in various species. However, in some polychaetes there are no special organs for respiration, and gaseous exchange takes place across the body surface.

• Many polychaetes have • respiratory pigments such • as hemoglobin, chlorocruorin, • or hemerythrin.

Class Polychaetes

Parapo

dia

Para

podi

a

Parapo

dium

Respiratory capillaries

Class Oligochaeta: The Earthworms• Earthworms have no special respiratory organs, but gaseous exchange occurs across their moist skin.

Class Hirudinida: Leeches

Gas exchange occurs only through the skin except in some fish leeches, which have gills.

Arthropoda• Unlike most animals, the arthropods have no single major respiratory organ. The respiratory system of most terrestrial arthropods consists of small, branched, cuticle lined air ducts called tracheae .

• These tracheae, which ultimately branch into very small tracheoles, are a series of tubes that transmit oxygen throughout the body.

Arthropoda• Air passes into the tracheae by way of specialized openings in the exoskeleton called spiracles.

• Most terrestrial arthropods have a highly efficient tracheal system of air tubes, which delivers oxygen directly to the tissues and cells and makes a high metabolic rate possible during periods of intense activity. This system also tends to limit body size. Aquatic arthropods breathe mainly by some form of internal or external gill system.

Arthropoda•In many insects, especially larger ones, muscle

contraction helps to increase the flow of gases in and

out of the tracheae. In other terrestrial arthropods,

the flow of gases is essentially a passive process.

•Many spiders and some other chelicerates have a unique

respiratory system that involves book lungs, a series of

leaf like plates within a chamber. •Air is drawn in and expelled out of this chamber by

muscular contraction. Book lungs may exist alongside

tracheae, or they may function instead of tracheae.

• One small class of marine chelicerates, the horseshoe

crabs, have book gills, which are analogous to book

lungs but function in water.

• Tracheae, book lungs, and book gills are all structures

found only in arthropods and in the phylum Onychophora,

which have tracheae. Crustaceans lack such structures

and have gills.

• In some very small insects, gas transport occurs

entirely by diffusion along a concentration gradient.

Consumption of oxygen causes a reduced pressure in

their tracheae that pulls air inward through the

spiracles.

• The tracheal system is an adaptation for air

breathing, but many insects (nymphs, larvae, and

adults) live in water. In small, soft-bodied aquatic

nymphs, gaseous exchange may occur by diffusion

through the body wall, usually into and out of a

tracheal network just under the integument.

• Aquatic nymphs of stone flies, may flies, and damsel

flies have a variety of tracheal gills, which are thin

extensions of the body wall containing a rich tracheal

supply. Gills of dragon fly nymphs are ridges in the

rectum (rectal gills) where gas exchange occurs as

water enters and leaves.

Insects

Insects• Inspiration: When the abdominal muscles relax abdominal volume is normal Oxygen from the air front stigma/spiracles (at the same time, abdominal stigma is closed) trachea tracheoles body cells

• Expiration: When the abdominal muscles contract abdominal voulume decrease results from respiration tracheoles trachea abdominal stigma/spiracles.