Browsers & Grazers

A major source of food on shores is algae. Some molluscs graze on the fronds of the larger green, brown and red algae. One of these is the Common Warrener, Turbo undulata. It grazes on algae at low shore levels.

Here are some Common Variegated Limpets, Cellana tramoserica, with a covering of algae on their shells, but no algae on the rock surface. Why is this so ?

It is estimated that for every square centimetre of limpet, about 75 square centimetres of encrusting algae is necessary to maintain its life during its first year of growth.

On many rock surfaces you can see the small round home scars of these limpets, and if you look carefully you can pick out the area which is grazed by them. If you remove the limpets from an area, you will notice that in a short time tiny algae clumps begin to sprout and grow. In areas where the limpets remain, the rock remains bare.

As these molluscs move across the rock they rasp their tongue, called a radula, across its surface. The radula is a file-like ribbon of small horny teeth that all gastropods and some other molluscs possess. It can rasp either vegetable matter, or flesh in some carnivorous species, and convey the particles of food into the mouth.

However, most browsers and grazers do not fed on large macroalgae fronds. They feed on microalgae, algae spores and small plants trying to gain a foothold on the rock surface in moist depressions and pools.

High Shore Browsers and Grazers

Some browsers at the Splash Fringe Level and High Tide Levels are:

Tubercled Noddiwink, Nodilittorina pyramidalis,
feeds on lichens at high shore levels

Blue Australwink, Nodilittorina unifasciata,
feeds on lichens at high shore levels.

Petterd's Limpet, Notoacmea petterdi

Mid Shore Browsers and Grazers

Some grazers and browsers of the mid-tide levels are:

Zebra Top Shell, Austrocochlea porcata,

Ribbed Top Shell, Austrocochlea constricta

Wavy Top Shell, Austrocochlea concamerata

Black Nerite, Nerita atramentosa

Striped-mouth Conniwink, Bembicium nanum,

Variegated Limpet, Cellana tramoserica

Low Shore Browsers and Grazers

Other grazers at the low-tide level and Low Fringe level are:

Black Keyhole Limpet, Amblychilepas nigrita

Elephant Snail, Scutus antipodes.

Common Warrener, Turbo undulata

References:

Bennett, I. (1987) W. J. Dakin's classic study: Australian Seashores. p,242, Angus & Robertson, Sydney.

Davey, K. (1998) A Photographic Guide to Seashore Life of Australia. p.88, New Holland, Sydney.

Shepherd, S. A. & Thomas, I. M. (1982) Marine Invertebrates of Victoria, Pt. 2. p. 553, South Australian Government Printer, Adelaide.

Underwood, A. J. & Chapman, M. G. (1993) Seashores: a beachcomber's guide. p.30, New South Wales University Press, Sydney.

Feeding Relationships

Nutrient Absorbers
Grazers & Browsers
Suspension Feeders
Deposit Feeders
Carnivores
Omnivores
Trophic Levels
Energy Pyramid

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