Beneath the Surface: Life along Port Stephens' rocky shores

Port Stephens hosts some of the state's most spectacular coastline.

Tomaree and Yacaaba headlands are well known icons, as are our sweeping sandy beaches and sheltered bays. It is however the lesser known rocky shorelines that perhaps present the most interesting and intriguing part of our coastline.

The rocky shoreline and its marine inhabitants are exposed to natures' elements; the drying sun, harsh onshore winds, daily tidal fluctuations and relentless wave action. Due to these forces only the fittest of the fit can survive life on the rocky shores.

Marine life of the rocky shores is specially adapted to survive in this harsh environment. Special attributes, such as shells with trap doors, have been developed to ensure sea snails don't dry out between high tides. Limpets and abalone graze algae on the rocks and possess a strong muscular foot so that they can avoid being swept off the rocks by wave action. Many of the animals also use camouflage to blend in with their surrounds and avoid any predators.

Barnacles are one of the most common animals found on the rocky shore just above the low water mark. Barnacles spend the early stages of life drifting around the ocean until they find a hard rocky substrate to settle on. They then secrete a cement like substance that fixes them to the rock for the remainder of their life. Being confined to the one place, barnacles rely on regular inundation by sea water to bring them their daily meals. Barnacles are referred to as filter feeders. They have hairy appendages, called cirri, that protrude from their shells and capture microscopic plants and animals found in seawater called plankton. When the tide recedes, the barnacles close their volcano shaped shell to keep from drying out in the sun.

Dr David Harasti with a seahorse.

Dr David Harasti with a seahorse.

Chitons are another example of a sea creature that is well adapt to life on the rocky shore. Chitons are a type of sea snail and are easily identified by the eight hard plates on their shell. They are herbivorous, feeding on both microscopic and larger algal plants. Chitons use their tongue to scrape algae off the rocks. The chitons tongue is called a radula and resembles something like a chainsaw; they are ribbon-like with minute teeth lining the edges.

Nudibranchs are one of the more colourful creatures found in rock pools. They can often be difficult to see at first as they are small and can blend in well with seaweeds and sponges. Often referred to as sea slugs, nudibranchs are a type of sea snail without a shell. The word 'nudibranch' means 'naked gills' and it is these feathery appendages which can most commonly be seen on the animals' back. Nudibranchs are one of the few animals that can feed on sponges. So, if you want to see these colourful critters, starting looking amongst the sponges next time you visit the rock pools.

The master of camouflage is one of the rock pools most elusive residents - the octopus.

Octopus have not only hundreds of different colour changes but can also change their skin texture. They can manipulate their boneless body to take the form of their surrounding environment so as to blend in. A number of species can be found in rock pools including the poisonous blue lined octopus. This spectacular octopus flashes iridescent blue rings all over its body as a warning to potential predators when it feels threatened. If you see any sort of octopus in the rock pools, be sure to look but not touch!

Be sure to stay safe when visiting rock pools and the rocky shore. Low tide is the best time to explore but be mindful of the sea. Always remain alert and watch for approaching waves. The rocks are often covered with algae which can be slippery when wet so be careful where you tread.

To showcase the Port's incredible underwater world the Examiner is collaborating with regular Bay divers and photographers on a new series that explores life Beneath the Surface.

Dr David Harasti is a senior marine scientist with the NSW Department of Primary Industries Fisheries, based at Taylors Beach.

Also in the Beneath the Surface series