Acetes sibogae australis (Colefax 1940), also known as the Australian paste shrimp or pygmy shrimp, is a small planktonic shrimp, common in sheltered coastal waters of eastern Australia. They are abundant in estuarine ecosystems, gathering in large schools in shallow water or structure such as near mangroves, jetties, bridge pylons and rock walls. Acetes can be considered the equivalent to the “Antarctic Krill” of temperate / tropic waters as they are the food source for hundreds of predators, including us humans (Vereshchaka, Lunina and Olesen, 2016). The individuals shown in this page were captured on the Gold Coast by the pylons of Tallebudgera creek bridge, during low tide. They are omnivorous filter feeders, staying in schools towards the upper-middle areas of the water column eating a variety of zooplankton and algae.

Classification of Acetes sibogae australis, Colefax 1940

Common Name: Australian Paste Shrimp
Kingdom: Animalia
Phylum: Arthropoda
Sub phylum: Crustacea
Class: Malacostraca
Sub class: Eumatacostraca
Super order: Eucarida
Order:  Decapoda
Family: Sergestidae 
Genus: Acetes
Species: Acetes sibogae
Sub Species: Acetes sibogae australis

Acetes sibogae australis is a small shrimp that has asimilar body plan to other Acetesspecies (omori). Acetes can be identified by a rostrum that is shorter than itseyes, as well as two dorsal denticles (sealifebase). Females larger than males.Fully transparent body, except for black eyes and long pale antennae, with tinyspecks of orange / red around the body. Gains a fully white / pearly colourthey die (refer to figure).

Females grow between 18-34mm in length and males 18-25mm.

Video 1. Australian paste shrimp swimming while being kept in an aquarium.

Australian paste shrimp use a variety of strategies to avoid predation. They school in large numbers, and react as a group darting in all directions when a predator attempts to attack. They move quickly through the water by beating their pleopods but are also capable of quickly flicking their tails to dart through or jump out of water. If a predator grasps or comes into contact with one of their long antennae it is able to drop it and use it as a decoy to escape. They do not appear to be affected by sudden changes in intensity of light, but are extremely sensitive to touch and visual movement.  

Acetes are oviparous, with females spawning their eggs into open water around 50m or shallower (Arshad et al, 2009). There is little data on long it takes for the shrimp to spawn after copulating, but for A. japonicus it takes 10-15 days (Omori 1975).
When the nauplius hatch from the egg, they have a similar morphology to those in the family Penaeidae. In the nauplius stage, it possesses a rudimentary carapace with the body and limbs undeveloped and unsegmented. As the gut is still incomplete in this stage, it can’t feed and lives off its supply of yolk (Xiao, 1993)
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The larvae is able feed and swim in its zoeal stage, using its antennae and antennules to propel itself. The maxillipeds and pereiopods are developed butun-functional in this stage.
In the mysid stage the pereiopods are developed, and the larvae begins to resemble the form of a shrimp. The antennae are no longer used for propulsion,with its abdomen developed enough to flick its tail for faster movement (Xiao, 1993).

14 Acetes species are distributed globally throughout temperate / tropical waters. Acetes Sibogae Australis has been recorded on the north and east coast of Australia in estuarine, coastal temperate / tropical waters. 

The family Sergestidae is divided into 2 sub-families. Sergestinae, comprised of 6 genera; Acetes, Peisos, Petalidium, Sergestes, Sicyonella and Sergia. And in Luciferinae the genus Lucifer (Omori, 1975). 

Acetes is identifed by a short rostrum with up to 2 dorsal denticles, with supra orbital and hepatic spines. 
They also only have 3 elongated pereiopods, with the fourth and fifth been lost entirely (Omori, 1975). 

Overfishing is a major threat for Acetes as it is the most fished crustacean in the world. Species are most at risk in south east Asia, as they are heavily pressured by pollutionas well as harvesting for use in fermented and dried food products.  Its popularity as a source of food also opens up opportunities in aquaculture. The more that is understood about Acetes the more effective the management of the fishery and aquaculture industry around it can become.

Arshad, A., Amin, S., Bujang, J. andSiraj, S. (2009). Age Structure, Growth, Mortality and Yield-Per-Recruit ofSergestid Shrimp, Acetes indicus (Decapoda: Sergestidae) From the CoastalWaters of Malacca, Peninsular Malaysia. Journal of Applied Sciences,9(5), pp.801-814.

Ball, E., Kao, L., Stone, R. andLand, M. (1986). Eye Structure and Optics in the Pelagic Shrimp Acetes Sibogae(Decapoda, Natantia Sergestidae) In Relation to Light--Dark Adaption andNatural History. Philosophical Transactions of the Royal Society B:Biological Sciences, 313(1160), pp.251-270.

Olesen, Jørgen. (2018). CRUSTACEAN LIFE CYCLES— DEVELOPMENTALSTRATEGIES AND ENVIRONMENTAL ADAPTATIONS.

Omori, M. (1975). THE SYSTEMATICS,BIOGEOGRAPHY, AND FISHERY OF EPIPELAGIC SHRIMPS OF THE GENUS ACETES. BULLETINOF THE OCEAN RESEARCH INSTITUTE UNIVERSITY OF TOKYO, 7.

Xiao, Y. (1993). Oceanographyand Marine Biology, An Annual Review, Volume 31. 31st ed. london: UCLPress.

Warrant, E. (2017). The remarkablevisual capacities of nocturnal insects: vision at the limits with small eyesand tiny brains. Philosophical Transactions of the Royal Society B:Biological Sciences, 372(1717), p.20160063.

Vereshchaka, A., Lunina, A. andOlesen, J. (2016). Phylogeny and classification of the shrimp generaAcetes, Peisos, and Sicyonella (Sergestidae: Crustacea: Decapoda).Zoological Journal of the Linnean Society.