BIOL 310 Excretion Osmoregulation Respiration

osmoregulation

maintains a balance of water and solutes in body fluid

accumulation of water in tissues or loss of water from body is a concern, due to osmosis the concentrations of salts in the internal body is often strictly controlled

osmotic pressure - drives osmosis, movement of solvent from low to high concentrations of solute

excretion

removes metabolic waste products (nitrogenous waster and co2)

nitrogenous waste is released through various methods structures and in various forms

the availability of water impacts how an animal will release waste passive diffusion is common in some aquatic inverts

nitrogenous water is main released as ammonia or ammonium (readily dissolves in water) but very toxic. Urea (rare in inverts) less toxic and can be more concentrated meaning need less water. Uric Acid (insects)/ Guanine (spiders) forms crystals needs like no water

estuary

area with mixing of freshwater and saltwater

littoral

from high water mark to shoreline that is continually under water

interstitial

area between particles in rocky and sandy shores could mean burrows

body fluids of inverts

are dilute saline solutions with sodium chloride as a prominent electrolyte

marine and freshwater are surrounded by very different environments

what straight forward factors influence metabolism

body size

activity

feeding

nuanced factors influencing metabolism

temperature oxygen tension and salinity

salinity

Changes in salinity can modify activity all animals must work to regulate certain ions/osmotic pressure of internal fluid either

close to equal to surrounding - osmoconformers

lower than surroundings - osmoregulators

or they just cant handle shifts

isoosmotic

when animal is at a low point of metbolism, they are iso osmatic with the surroundings then when salinity changes metabolic rate increases animals work harder to survive

whereas estuarine animals deal with this constantly and have adapted to the conditions so metabolism decreases sharply as salinity differs from normal marine- suffer more in dilute. freshwater-suffer more in concentrated

echinoderms

their blood is basically sea water no regulation of body fluids

the only ion that is regulated is K

possible reason they haven’t invaded freshwater or land

cnidaria Aurelia

mollusca Speina

keep So4 very low and actively replace with Cl giving them really light tissues

adaption for buoyancy

cuttlebone

contains many chambers holding gas and others that contain high NaCl fluid

helps with buoyancy

plus they can change the ratio of gas filled:fluid filled aresa

the invasion of land

3 routes

sea-estuary-lake-land

sea-littoral- land

sea - interstitial - land

no matter where they travelled from the common origin was the ocean (body fluids are dilute saline solutions with sodium chloride)

but there are some modifications

freshwater inverts

osmoregulators

soft bodied tend to maintain lower osmolarity relying on intracellular osmotic regulation

hard bodied tend to maintain higher osmolarity - shells dont let water in so they keep more salt

use active transport

marine inverts

generally osmoconformers matching internal osmolarity to seawater

land inverts

knowing that extant marine inverts have higher osmotic pressure than freshwater inverts

we hypothesis

terrestrial invertebrates that originated in marine env have higher internal osmotic pressure than terrestrial inverts originated from freshwater

most inverts invade from marine

exceptions of land invert hypothesis

this is probably true in some cases but nemertans that moved from marine to terrestrial (A dendyi) has very low osmotic pressure

because interstitial animals are buffered from changes in salinity of overlying water by the sediment. closer to show interstitial water becomes very dilute and inverts develop ionic regulation and keep similar to those

Terrestrial Decapod has high osmotic pressure even though likely invaded from freshwater

extant small freshwater decapods do have low osmotic pressures but larger species maintain similar to marine, hard exoskeleton is generally impermeable to water but conserving water is still critical, ammonia as an excretion product is a challenge bc need lots of water

land crab gills

multi-functional

• respiratory gas exchange

• excrete nitrogenous waste

• regulate acid base balance

• osmoregulate and ion transport

• reabsorption of salts from primary urine

they release ammonia as gas! to deal with water. concentrated hemolymph contributes to ammonia excretion via the gills as aerosolized ammonia (sometimes they also just chill in freshwater to regulate)

adaptations to land

body surfaces to resist drying (desiccation)

some dehydration will happen occasionally, increase in osmotic pressure of body fluid

a marine ancestry will provide more flexibility in adapting to these fluctuations (freshwater are in major danger with just a little dehydration)

soft bodied inverts on land

maintain a moist surface live in moist environment

exoskeleton inverts on land

prevents water loss mainly from epicuticular wax so they dont need as much water

take up water from drinking or metabolism

highly adapted

adaptions of freshwater to dilute conditions (ex mussles)

osmoconformers

have fast acting enzyme variations (which is very common in low salinity)

the intracellular fluid is regulated by concentration amino acids

because of a genetic component with enzymes in amino acid production making them more efficient

mussles are one example they have variation in leucine aminopeptidase enzyme (across diff salinity)

adaptions of freshwater inverts osmoreg

some are osmoregulators

must have control in water influx and removal of ions from body

less permeable body produce lots of urine to offset influx of water but that means many ions lost

Maintain dilute body fluids less energy required if it close to that of surroundings

many of these guys actively transport specific ions to the body directly from surroundings

two categories of excretion/osmoregulation structures based on development

1. tube developing from ectoderm then growing inward (out-in) nephridia

2. tube developing from mesoderm then growing outward (in-out) prostomia

fundamental processes in excretion

ultrafiltration cell membranes

active transport

nephridia

tube developing from ectoderm then inward

two main types

1. protenphridia

2. metanephridia (annelida)

protenphridia

(nemerteans, rotifers polychaetes, cephalochordates) primarily for osmoregulation.

Constantly releasing water through nephridia. flame cells create neg pressure to drive liquids through membrane.

its simple. blind ended tubes with motile structure (flame cell) to drive flow.

flame cells take in and preform ultrafiltration the cells are packed with active transporters

metanephridia

active transport af! to harvest ions and ultrafiltration less of a role

in oligochaetes, brachiopods, sipunculans

repeating pairs septae separates body cavity

opens at both ends and is multicellular filters large columes of body fluid

protonephridia only open to outside of animal

goes through the nephrotosom to through septum and out the excretory opening

coelomoducts

tube developing from mesoderm then growing outwards (arthropods some, molluscs, some annelids

develops from the gonad, releasing gametes may be primary function, have fused with nephridia to serve dual role

tubular only sometimes ciliated

in crustaceans have green/ antennal glands

crustacean green antennal gland

open at base of the 2nd antennae or 2nd maxillae

osmotic pressure changes most significantly along nephridial canal

pressure of haemocoel forces material through the system

Pressure of blood drives liquids to antennal glans cause of high internal pressure

active transport through nephridial canal

no cilia

in decapods work alongside excretion across gills, well ventilated branchial chamber, gill bailers mover water over gills, and ammonia is excreted from gills

malpighian tubles

no relation to nephridia or coelomoducts

present in tardigrades, insects, arachnids, thought to not be homologous between taxa

are long slender blind ended tubes that empty into digestive tract, soluble uric acid is transported to blind end, acidic lumen uric acid and water is reabsorbed (energy intensive)

this is to scavenge water because uric acid goes to feces blind ended tubes from hindgut lead to digestive tract becomes acidic causing uric acid to precipitate

the role of oxygen

molecule that is taken up at respiratory surfaces/organs and used to oxidize organic molecules to generate ATP

cellular respiration

produces energy from food sugars

cellular respiration requires oxygen to break down food molecules, the energy released from catabolism is used to generate ATP

carbon dioxide and water are by products of cellular respiration

how are invertebrates absorbing o2

passive diffusion across body wall (with or without circulatory systems)

specialized gas exchange organs (gills, respiratory cavities(book lungs trechea etc) in this water is often forcefully pushed over respiratory surfaces

passive diffusion of o2 across body wall

moving across tissue from high to low concentration

influenced by partial pressure of oxygen and properties of the body wall tissue

rate of diffusion defined by ficks law

Q=DA * (P1-P2)/L

diffusion rate = coefficient*area diffusion must occur over (concentration gradient)/distance over which diffusion occurs

large gradients have faster diffusion

based on the assumption that the farsest metabolizing tissue can be from the surface is 1mm (big reason why platyheminthes and nemerteans are dorsoventrally flattened) if too thick o2 won’t get deep enough since no circulatory structures

a good circulatory system could allow larger bodies to have passive diffusion

passive diffusion in cnidaria

these are ticker animals then 1mm but the mesoglea has no cells so no oxygen in there

and they have low metabolic demand and thin tissue

the stomach contains oxygenated water that flows through

how do larger animals absorb o2

have organized circulatory system that allows for larger size

allows the movement of o2 containing fluids throughout the body to reach deeper tissues

ensure that liquid in contact with respiratory surface has low o2 (steep po2 gradient)

also allows impermeable coverings like shells

circulation

more active animals will have closed systems

sluggish animals have open systems and low blood pressure

passive diffusion in annelida

closed circulatory system and specialized areas of the body for respiration (often parapodia)

muscular, pulsating vessels to circulate liquid through the body - hearts

parapodia are highly vascularized and contain many blood vessels

they are an important respiratory surface

annelids and many other inverts have respiratory pigments, dissolved in blood plasma and cells of the coelom

what moves through the circulatory system

blood = hemolymph (varies across inverts) may be colourless with no oxygen-binding pigments urochordates and hemichordates

respiratory pigments provide colour

• with oxygen binding pigments the capacity is 2-30 x more than colourless. commonalities in structure

hemocyanin, hemerythrins, hemoglobin - all bind reversibly with oxygen all are metallo-proteins all change colour under oc vs deox

respiratory pigments are found in 1/3 of phyla and theres not one point of origin

hemocyanin

always dissolved in hemolymph

found in arthropods and molluscs

does not contain heme, iron, or porphyrins

active site contains CU

colourless when deoxy blue when oxy

hemerythrin

always intracellular circulating coelomic cells or muscle cells

does not contain heme group but do contain Fe

found in 4 lophotrochozoans (spinculins, priapulids, megalona, brachiopoda)

colourless deoxy pink oxy

hemoglobin

found within nucleated cells or dissolved in hemolymph

found in many taxa including nematodes some annelids some crustaceans some insects vertebrates

counter current flow

an underlying concept in respiratory surfaces

ensures largest gas exchange over entire structure

water flow and blood flow opposite direction which allows blood to get to same oxygen levels as water

specialized gas exchange organ in crustacea

gills are the respiratory organ vary greatly in form location and development

commonly found on appendages, epipodites or inside branchial chamber of cephalothorax

water currents created by beating appendages or gill bailers for thoracic gills

hemolymph may contain hemoglobin or hemocyanin

specialized gas exchange organ crustacea - isopoda

thin cuticle on flattened pleopods is respiratory surface, strongly wrinkled increasing surface area

may be enclosed in a chamber opening to outside via a spiracle

specialized gas exchange organ echinoderms

respiratory system involves the large surfacce area of the water vascular system

simple passive diffusion over those surfaces

papulae in sea stars differ in other classes

coelomic fluid not blood is transport medium pigments may be present bound within cells in wvs

inner outer surface of podia and papulae are ciliated move liquids past their surface counter current flow

specialized gas exchange echinoderms - holothuroidea

respiratory trees - derived characters of the class, highly branched muscular respiratory structures

paired chambers within the body extend into the coelom

muscular cloaca pumps water in through the anus

gas exchange occurs across tree walls

muscular resp tree contracts to force water out

moving to land with gills

gills do poorly on land some animals put gills into cavities and others developed new respiratory structures/cavities

respiratory cavities

insects and some ecdyszoa

circulatory system not involved in respiration

open to outside world at the spiracle

more advanced tracheal system in arthropods, branching with canals that allow air to infiltrate to deep lying tissues

tracheoles are the smallest branches each in insect body are contracting a tracheole in insects the tracheal system is filled with fluid for gas exchange

chelicerate respiratory cavities

have book lungs and book gills

homologous structures originally evolved for breathing underwater

hemolymph-filled lamellae project into enclosed space

connected to outside by spiracles some also have tracea

book lung and tracheal systems

are present in some arachnids supply a very large oxygen demand particularly when molting

no apparent control of tracheal volume/pressure

mollusc gill ctenida (bivalves prosobranch gastropods)

internal gills, bipectinate mostly, lateral cilia to create current

open circulatory system hemolymph is the blood, most bivalves do not have respiratory pigments, some families have free circulating hemoglobin not associated with cells

majority of marine snails includes limpets concehs cowires, whelks

mollusc gill nonciliated ctenidia (cephalopods)

internal gills, bipectinate(narrow projections like the teeth if a comb) muscular contraction of the mantle and a closed circulatory system

very efficient respiratory system because of adaptations ie hearts and closed

respiratory pigment is haemocyanin cu based pigment

mollusc gill

heterobranchs (different gilled)

revised clade that includes the gastropods with alternative respiratory structures

formerly the opisthobranches

gastropod lungs

plumonates

common terrestrial/freshwater snail slug

have shell without operculum or lacks shells completely commonly have hemoglobin as respiratory pigments

ctenidia have been lost

inner surface of mantle cavity has become vascularized - tissue lining the mantle is the site of gas exchange. The pnemostome is the muscular opening to the lung

nudibranchia respiratory

sea slug

shell and mantle absent

respiratory structure are external and may be:

• ctenidia arranged on the dorsal surface gill rosettes

• dorsal projections as the respiratory surface ctenidia lost cerata

• respiratory surface only on ventral surface under mantle body is bilaterally symmetrical with anus at posterior

• respiratory surface only on ventral surface under mantle

aeolid nudibranchs

a clade within nudibranches

have secondarily derived respiratory structures for respiration

cerata are outgrowth on the dorsal region highly vascular, variable shape, often brightly pigmented

gut may extend into the cerata

cerata may also contain harvested cnidocytes from hydrozoan prey

body size influence on metabolism

larger inverts need to take up more o2 more body volume greater o2 needs

o2 uptake is relative to surface area

sa increases much more slow than vol

supports the need for specialized respiratory structures in larger inverts sa of these structures can be somewhat independent of body vol

activity and feeding influence on metabolism

active inverts need to take up more o2 than less active o2 consumption increases immediately after feeding then subsides

temperature influence on metabolism

poikilothermic - large variation in body temp

bu many inverts live in fairly consistent conditions

ectothermic - external source of heating

acclimation - mussels moved from 10 to either 5 or 25 have quick influxes in metabolism then adjust to stable level - acclimation for energy conservation/ATP production maintenance, some inverts dont normalize metabolic rate (continue to increase when warm or deacreas when cool, (neg acclimation))

so littoral inverts face larger temp fluxs and are competent pos acclimators

inverts that hibernate are neg acclimators

temperatures vs flying

some flying insects must have some control over their body temp to fly in more temperate zones insects must generate body heat (endothermy) to maintain constant body temp (homoethermy)

temp of flight muscles 30-44 degrees temp controlled by regulating flight activity, body fluid act as coolant, insulating hair on thorax

sometimes butterflys even shiver to warm their muscles up

oxygen tension on metabolism

normoxia, hypoxia, anoxia

generally hypoxia tends to be aquatic is a big issue for them

when low PO2 some inverts cannot maintain normal levels of metabolism (oxyconformers) - includes mayflys, stonfly, sponges, cnidarians marine arthropods and nearly all terrestrial inverts

many aquatic organisms can adapt to low po2 and maintain consistent levels (oxyconformers) but even that have a value that they cannot adapt to (critical Po2)

oxyregulator adaptations

change physiological process to adapt only a short term response and still causes stress

long term solutions - produce more respiratory pigment decrease metabolic demand, escape

for most response is escape which may require intense work but better than death

daphnia adaptations

oxy rich oxy poor changes gene expression of hemoglobin

within few days whole animal becomes red in response to low o2