Neptune’s Necklace Richard Ling

Neptune’s Necklace

Hormosira banksii

Did You Know?

  • Eaten by sea urchins, crabs and fish
  • Its dense colony of fronds forms a protective microhabitat where molluscs, worms and small crustaceans shelter
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Its species name banksii is after the English naturalist and botanist Sir Joseph Banks.

A small, brown seaweed (algae) which resembles a beaded necklace. It has branches (thalli) which are made up of strings of hollow, water-filled, round or oval-shaped beads joined together by a short stalk. Each bead is covered in many pores, giving it a rough surface. It is attached to the substrate by a thin disc (holdfast).

Size

Fronds 10 – 30 cm long, beads 5 – 15 mm in diameter, and holdfast 3 – 10 mm across.

 

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What to Observe

Search area for 30 minutes and record the following:

  • Abundant: found easily with little searching

  • Frequent: found with minimal searching

  • Rare: only 1 or 2 individuals found with intensive searching

  • Not found: not present during search

Climate Adaptations

Black Nerites, like all marine snails (molluscs), are under increasing stress due to ocean acidification which can weaken their calcium carbonate shells and reduce body condition. This makes them more prone to disease, predation and low reproduction. Increasing water temperature as a result of climate change will likely affect their abundance and cause a southward shift in their distribution.

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When and Where

When To Look

  • Throughout the year

Where To Look

  • From King George Sound in Western Australia, around southern Australia and Tasmania to Port Macquarie in NSW
  • Also found at Lord Howe Island and Norfolk Island
  • In the intertidal zone, on rocky shores and in rock pools
  • Usually attached to rocks and often occurs in vast colonies forming a thick cover
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What Else?

Similar Species

It is a very distinctive seaweed. Other seaweeds are often larger, brown in colour and have leaf-like rather than bead-like fronds.