Botany Bay Ecosystem

What lives in botany bay

Where is Botany Bay?

Botany Bay is located about 13 km south of the Central Business District of Sydney and has it's source of water coming from the confluence of the Georges River and Cooks River. It then flows for approximately 10 km east before it meets the Tasman Sea.

List of organisms that live in Botany bay

  • Blue-swimmer crab
  • Semaphore crab
  • Pipe fish
  • Shrimp
  • Pigmy Squid
  • Pelican
  • White faced heron
  • Leather Jacket

Abiotic and Biotic factors

Abiotic factors are the factors in an ecosystem that are non-living. These include:

  • Tides - Tides change through out the day and as a result so do the behaviors of the organisms that live in the sea grass beds and in the mangroves. In low tide, organisms which live in the beds are more susceptible to predators such as birds who couldn't normally feed on them because of the water. Another aspect that changes with the tides is the amount of light that reaches the creatures.
  • Temperature - Temperature changes from place to place throughout the Botany Bay ecosystem which is one reason why creatures like crabs are more likely to be found in the mangroves. This is a place where it is cooler as there is protection from the light and heat.
  • Light - The amount of light changes with the tides and shade in different areas. Light may effect some organisms as when lux is higher then prey are more easily spotted by predators.

Biotic factors are those that are living in the ecosystem.

  • Grey Mangroves - The mangroves are essential to life in Botany Bay for many ecosystems. The mangroves not only provide shelter for birds, crustaceans, mammals and fish, but they also filter pollutants and stabilize the soil which decreases erosion as the soil is dragged back into the ocean by the waves. Mangroves are also a very important part of the food chain as many herbivores eat the leaves, fruit and flowers of the mangrove.
  • Sea Grass Beds - Sea grass beds are also very important in the ecosystem as they stabilize sands and sediments because of their roots. Many organisms use the sea grass beds to hide from predators and hunt for prey such as the pipe fish and pygmy squid.
  • Fungi - Fungi breaks down the leaf litter from the mangroves increasing it's protein and making it food for the fish and shrimp in the process. They themselves produce a waste which is also food for the mollusks and smaller crustaceans.

Human Impact on Botany Bay

Humans have impacted Botany Bay ever since white settlement in 1770. Ways that humans have impacted Botany Bay include:

  • Weeds - As a result of clearing of native vegetation in the 1860's for agricultural purposes, weeds have been able to invade these areas. This means that the native plants also then have to compete with the weeds for space, nutrients and sunlight.
  • Boats - Anchors used by boats to stop them floating away, destroy the sea grass which is used by organisms such as the pipe fish and shrimp as a place to hide from larger predators. This will effect the entire food chain as the population number for that species will decrease and therefore whatever that prey eats will overpopulate causing a domino affect.
  • Feral Animals - Feral animals such as foxes have become a problem for native animals in the environment. Foxes are native to North America and came here as a result of white settlement. The native wild life now has to compete for food, shelter and habitat, and many have had to deal with new predators which they don't know how to protect themselves against.


Semaphore Crab (Heloecius cordiformis):


The semaphore crabs live on the mudflat which is in the inter tidal area, in the mangroves near an estuary or bay. There environment is cold and wet or damp as there are mangroves to protect the crabs from light and wind. The mud is malleable and so it is easy for the crab to burrow quickly to escape.


The semaphore crab is a detritivore which means that it will eat almost any dead material that it can find, which includes fallen leaves or dead organisms. It will also eat algae and micro-organisms.


  • Burrows into the mudflat when it feels threatened for protection and can do so quickly as the mud is malleable and it has large claws.
  • Stands at the top of it's burrow with it's claws raised in the air to either warn away males or show off to females. Females would be interested in a crab with larger claws as this would be a good trait for him to pass on to her zoea.
  • Eyes are on top of stalks which allows it to check for predators before it leaves it's burrow.
  • Can breathe on both land and under water. This adaptation allows the crab to live where it does which is on the mudflat. As a result of tides changing throughout the day the mudflat is sometimes covered by water and sometimes not.

Pygmy squid (Idiosepius notoides):


The pygmy squid lives in the sea grass beds which are found at or near the low tide mark in sheltered bays and estuaries. Despite it's name the sea grass is not actually grass but rather has grass-like leaves that grow out of the persistent sheath which is different to normal grass in which the blades grow from the internode. The squid uses these long and thin leaves to it's advantage when hunting.


The pygmy squid feeds of the small crustaceans such as shrimp that live in the sea grass beds with them. They hide on the underside of the leaves using their 'glue glands' and when a shrimp is unlikely enough to swim past then the pygmy squid swims up behind it and bites its nerve cord to immobilize it.


  • Glue glands release a sticky glue that allows them to stick to the sea grass or cover themselves in sand to help them to camouflage as they wait for prey.
  • Sharp beaks that allow them to bite through the nerve cords of its prey so that it can feed.
  • After the pygmy squid has found a partner to mate with and it is time for her to lay her eggs, she goes to the bottom of the sea grass beds and lays her eggs and then she covers them in a protective layer of the substance from her glue glands. These eggs then stick to the bottom of the plant where the male fertilizes and re-fertilizes the egg to maximise the number of organisms produced in the water environment.
  • When the squid is not in the protection of the sea grass and need to camouflage as a defence, then they change the way that light bounces off their skin through their light reflecting cells called iridophores.
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Food Web

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Reliability of Resources

To make sure that the resource's information was reliable I checked multiple websites to see if the information corresponded correctly. (only one site was listed below). As well as this the author for each website was checked to find out if they were reliable.


"Feral Animals In Australia | Department Of The Environment And Energy, Australian Government" N.p., 2016. Web. 9 Sept. 2016.

"Genesis - Pygmy Squid Laying Eggs". Vimeo. N.p., 2012. Web. 13 Sept. 2016.

"Pygmy Squid". Sea Creature Fact of the Week. N.p., 2016. Web. 13 Sept. 2016.

"Seagrass And Seagrass Beds". Ocean Portal | Smithsonian. N.p., 2013. Web. 11 Sept. 2016.

"Semaphore Crab". N.p., 2016. Web. 11 Sept. 2016.

"Semaphore Crab - Australian Museum". N.p., 2010. Web. 10 Sept. 2016.

"Semaphore Crab Illustration - Australian Museum". N.p., 2009. Web. 11 Sept. 2016.

"Southern Pygmy Squid – Idiosepius Notoides Berry, 1921 - Australian Museum" N.p., 2010. Web. 12 Sept. 2016.

"Towra Point Nature Reserve". N.p., 2016. Web. 9 Sept. 2016.