Adaptation of Rocky shore organisms

Adaptation of Rocky shore organisms

Adaptation shown to protect from desiccation & wave action

ž  Adaptations are morphological,physiological and behavioural

ž  Morphological & structual adaptations are changes in the shell(closing ability),strong foot (press against the substrate),colour changes, secretion of cement / byssus thread.

ž  Physiological adaptations: changes in the temperature of the body,changes in respiratory pattern(become anaerobic ) ,changes in excretory products,loosing the weight and changes in osmoregulatory patterns.

ž  Behavioural  adaptations include  quick burrowing or changing locations which are unfaurable and getting in to hiding places.

Littoral fringe zone adaptations

ž  Littorina : can survoive out of water for week. Those live upper shore are lightly coloured to reduce heat absorbtion.

ž  Having ridges on the shell to increase the reflection of light.

ž  Litorina can retract completely in side the shell opening with operculum.

ž  Attached to the substrate by mucus thread.

ž   even when fully retracted in shell mantle cavity holds considerable sea water provides moisture during evaporation.

ž  Avoid hot sun by seeking crevices  or shady side of the rocks.

ž  They produce insoluble uric acid as their excretory product thus water needed for excretion is reduced.

ž  Although they live in high exposed zone thete are herbivore feed on they do not depand on water for feeding & reproduction.

ž  Isopod  Ligia /sea slater is a fast runner in days they seek caves & crevices for protection from predators & exposure.

Eulitoral zone adaptations

ž  Have to protect them from wave action ,desication & other environmental stress.

ž  Acron barnacles (Balanus) secrete dtrong caco3 box that protect them from wave action.

ž  Firmly attach them to rocks by tightly  bonding glue.

ž  They tightly close their shell plates to prevent desication

ž  When prolonged exposure they also close micropile and switch to anaerobic respiration.

ž  Cypris larvae of barnacle is to choose the site for attachment.

ž  Mytilus like mussels produce byssus thread to attach with rock.

ž   they close the valve tightly to prevent desication  & can become anaerobic.

ž  Mussels live clumped to break the force of wave byssus thread trap sediments & create moist micro habitat.

ž  Sea urchins are found in burrows .

ž  Oysters firmely attached to rock by cement.& close valves tightto prevent evaporation , bottom shell valve is curved to trap water.

ž  Limpet has cone shape shell & cling to substrate by long ventral foot.

ž  Foot is mucus covered, water held in the mantle cavity prevent desication

ž  Secretion of mucus band aroun the edge of the shell.

ž  Limpet can tolerate loss of  65% of water this is the adaption of weight loss.

ž  Trochus & Cowris can withstand wave action by having heavy shell.

ž  Chiton has broad foot to press fermly against the rock.

ž  Decapod crabs seek out crevices & under side of rock their bodies are flatten to creep between narrow crevices.

ž  Black crapase as rock colour prevent from detection by predators,retain sea water in the gill cavity

ž  Yong of the crabs found among algae & sea weeds to protect them selfs from waves.

ž  Amphipod isopods also creep among sea weeds theis body is laterally flatened to creep among algae.

ž  Sea anemones found in crevices & creeks to avoid direct wave action.

ž  Retract their tentacles & shrink their body.

ž  Nereis escape from wave by being in side the tubes which are attached to rock.



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