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Sheltered Sandy Shore

Habitat

Coastal Organisms 
 
Marine Organisms
 

Habitat

Sandy shores can be divided into an exposed or a sheltered type, depending on the strength of wave action the shore receives.  The sandy shore in Ting Kok is a sheltered type, which means it receives weaker wave action, and has a substratum composed of sand with smaller particle size as compared to an exposed sandy shore.
 

 
With fine sand particles and stable condition, the substratum can retain more moisture in the sheltered shore which results in containing higher species diversity and a large quantity of organisms than those of the exposed shore.  
 
Nevertheless, the distribution of species is determined by ecological gradients of shore. Ecological gradients include vertical gradient, horizontal gradient and depth gradient.

 

i) Vertical gradient is caused by tidal cycles.  Sand in the lower intertidal zone only dries out on the surface during low tides, whilst sand in the upper intertidal zone dries out to a greater depth for a longer period.  Being uncovered by tides, the upper intertidal zone normally exposes to air and experiences more extreme temperature change than the lower intertidal zone.  Therefore, organisms inhabiting in the upper intertidal zone are expected to be more capable of coping with water stress.
 
ii) Horizontal gradient is created by local topography and oceanography.
 
iii) Depth gradient is determined by oxygen availability and particle sizes of the sandy shore.  Generally speaking, oxygen availability decreases as you go deeper to the ground.  Sand gets darken in colour is due to the action of anaerobic bacteria.

In addition, boulders and rubbles patchily scatter on the sandy flats in Ting Kok, forming scattered gravel shores along the sandy shore. 
 

At first glance, this type of shore may look dull.  Nevertheless, if you observe carefully, you will discover a dynamic habitat.  No matter on the hard surfaces of boulders and rubbles or the crevices and spaces under them, boulders and rubbles can provide homes and refuge for different kinds of organism to escape from hot sun, dehydration and hide from predators, for instance, the shore birds. 


Brachidontes variabilis
 
Common Rock Oyster
Saccostrea cucullata
     

Barnacle
Amphibalanus amphitrite
 
Isognomon ephippium
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Coastal Organisms

Organisms on sandy shores can be categorised into three groups by their ways of habitation: 

i) Surface dwellers, which are collectively referred to as “epifauna”.  Most of the epifauna are mobile crustaceans such as crabs.  They are usually scavengers, feeding on dead animals or detritus on top of the sand.  Some of the epifauna possess a comprehensive camouflage to mask themselves from predators and preys.

 


 Metopograpsus frontalis
 
Topshell
Monodonta labio
 
Soldier Crab
Mictyris sp.
         

 Fiddler Crab
Uca crassipes
 
Fiddler Crab
Uca borealis
 
Ghost Crab
Ocypode ceratophthalmus 
         

Buddhist Crab
Tmethypocoelis ceratophora
 
Swimming Crab
Thalamita crenata
 
Sesarmine Crab
Perisesarma bidens
         

Sesarmine Crab
Parasesarma pictum
 
Turban Shell
 Lunella coronata  
  Hermit Crab
Clibanarius longitarsus 
  
 
ii) Burrowers, which are collectively known as infauna, including both shallow and deep burrowers.  Most infauna are bivalves and worms.

 


Anomalodiscus squamosus
 
Caecella sp.
 
Ruditapes sp.
         

Anadara cornea
 
Gafrarium sp.
 
Marcia sp.
         

Siphonosoma cumanense
  Innkeeper Worm
Ochetostoma erythrogrammon
   

 

iii) Temporary burrowers, which may be surface dwellers or burrowers, depending on the phases of tidal cycle.

 


Terebralia sulcata
 
Batillaria sp.
 
Cerithidea sp.
         

Dog Whelk
Thais clavigera
 
Nassarius festivus
 
Clithon sp.


No matter living on the sand surface or within the sand, animals have to face different challenges.    
 
Living on the sand surface allows animals to search for food or mates easily.  However, since the shore is exposed to air and intense solar radiation at low tide, organisms are at the risk of water loss and heat stress.  They are also easier to be washed away by waves.  
 
Oppositely, organisms living within the sand are safe from wave action, predation and desiccation during low tides.  However, they have to face challenges in finding food, mates and enough oxygen for survival. 

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Marine Organisms


Pistol Shrimp
Alpheus brevicristatus
 
Green Urchin
Salmacis sphaeroides
 
Starfish
Luidia maculata
         

Jellyfish
 Mastigias papua
 
Starfish 
Archaster typicus
 
Sea Cucumber
 Holothuria leucospilota
         
 Flesh-Crested Blenny
 
Omobranchus fasciolatoceps
 
Spotted Seahorse
 Hippocampus kuda 
 
Sea Squirt
 Styela plicata
         
Pipefish
Hippichthys
sp.
   Striped Sweetlips
 Plectorhinchus diagrammus
  Hong Kong Pufferfish
Takifugu alboplumbeus
         

Striped Poison-fang Blenny Mimic
Petroscirtes breviceps
 
Sleepy Goby
Psammogobius biocellatus
 
Freckled Goatfish
Upeneus tragula  
         
Slender Sliver-biddy
Gerres oblongus
 
Butterfly Ray
Gymnura sp.
  Fan-bellied Leatherjacket
Monacanthus chinensis
         
 Broadbanded Cardinalfish
Ostorhinchus fasciatus
  Longhorn Cowfish
Lactoria cornuta
  Fingered Dragonet
Dactylopus dactylopus
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Last Review Date : 27 August 2015