Download Invertebrate Anatomy and Physiology

Invertebrate anatomy and
physiology
Aka: invertebrate form and
function
Invertebrate physiology: Skeletons
• Three kinds of skeletons are seen in
Invertebrates
• Hydrostatic
– Muscles surround and are supported by a
water filled cavity
– No hard structures for muscles to pull against
– Diagram on page 814
Invertebrate physiology: Skeletons
• Exoskeleton
– External skeleton, muscles are attached to
the inside (page 815)
– Arthropods are the best examples
– Made of the carbohydrate chitin (remember
from fungus)
– All exoskeletons are thin a flexible at the joints
– Advantage: very adaptable, very strong
– Disadvantage: in order to grow the anima has
to molt
Invertebrate physiology: Skeletons
• Endoskeleton (page 815)
– Located inside the body
– Present in sponges and echinoderms
– Vertebrate are the best examples
Invertebrate physiology: Digestion
•
Two strategies:
– Digestion inside cells and digestion outside cells
– Diagrams on page 784.
•
Inside cells:
– 1) Intracellular digestion
– In sponges, cells filter particles of food in the water, digestion occurs inside the
cell, digested products transported to other cells
– 2) Gastovascular cavity digestion (seen in cnidarians and flatworms)
– Food goes into a digestive cavity with only one opening to the outside, food
broken down in the cavity, smallest particles taken into the cell, waste eliminated
through the opening
•
Outside cells:
– Tube within a tube plan, food enters a mouth and exits an anus
– Food is digested inside this digestive tract; digested food is adsorbed into the
cells
Invertebrate physiology: Internal transport
• Two kinds of circulatory systems
– 1) Open circulatory system
– 2) Closed circulatory system
• Open circulatory system
– Blood from the heart is not contained inside blood vessels
– Example: insects
– Blood contacts all the tissues of the body
• Closed circulatory system
– Blood is contained in a system of closed vessels that pass
through various parts of the body and return to the heart
– Example: earthworms (diagram on page 792)
– Provides more rapid and efficient control of blood flow
Invertebrate physiology:
Respiration
• Two physiology problems:
– Surface area needs to be large enough so that gas exchange by
diffusion is adequate to support the animal
– Gas exchange surfaces must be kept wet because gas
exchange happens by diffusion only across wet membranes
– Diagrams on page 788-789
• Adaptations
–
–
–
–
Worms respire through their skin
Crustaceans have gills
Spiders have book lungs
Insects have trachea (tubes that carry oxygen to each cell)
Invertebrate physiology: Excretion
• Purpose is elimination of toxic waste
• Closely related to control of water loss
–
–
–
–
Breakdown of amino acids produces ammonia, which is water-soluble
Elimination of ammonia means losing water
Salt-water animals eliminate ammonia by diffusion into the water
Freshwater flatworms have specialized cells Flame Cells to remove
excess water (why??, remember osmosis) and ammonia
– Annelids, mollusks, invertebrate chordates have specialized organs to
remove ammonia from water, eliminate the ammonia in urine and return
most of the water to the organism
– Land invertebrates convert ammonia to urea, which can be made more
concentrated than ammonia, but is still soluble in water
– Insects and some spiders convert ammonia into uric acid, which is
removed by organs called Malpighian tubules. Uric acid is excreted as
a solid waste. This system conserves the most water.
Invertebrate physiology: Response
• Specialized cells for response to the environment are called nerve
cells
• No matter what the animal, nerve cells look and function pretty much
the same
• Primitive invertebrate have nets of nerves distributed throughout the
body
• Two advances in development of nervous systems:
– Some jellyfishes show Centralization where nerve cells are
concentrated into a system around certain organs like the mouth
– Clumps of nerve cells are called ganglia. Ganglia located near the head
result in Cephalization, gathering nerve cells in the front of the organism
where the animal first senses its environment.
– Insects and mollusks show development of ganglia into brains
– Nervous system development coincides with the development of
specialized sensory cells like eyes.
Invertebrate physiology:
Reproduction
• All invertebrates are capable of sexual
reproduction
• Creates and helps maintain genetic
diversity