Well as we end a quite cold and rainy August we can look forward to one last bank holiday, and the joys of a warm September. As we speak the first Minotaur Beetles (last week’s issue) will be emerging from their burrows. This week’s creature also lives in a burrow, but has a much darker side than any lumbering dung beetle. Hope you guys enjoy the issue…

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Issue #84 – Harlequin Shrimp

Kingdom – Animalia

Phylum – Arthropoda

Class – Malcostraca

Order – Decapoda

Family – Hymenocieridae

Genus – Hymenocera

Species – picta

Related Species – H.picta is one of two species in the genus Hymenocera, the other being H.elegans (1)

Range – Harlequin Shrimp are found on coral reefs in the Central and Eastern Pacific

Dark Secrets of the Harlequin

Harlequin Shrimp are medium sized shrimp, with a body length of 5cm, and are covered in bright purple and red spots across their body. The shrimps head features eye stalks that look as if they have been flattened, flanked by a pair of petal like organs called antennule, that detect chemical cues released by both predators and prey (2). The claws are larger than shrimp of similar size, and are used to flip heavy prey and dig through corral rock.

Harlequin Shrimp hunt in pairs, usually containing one female, and the slightly smaller male, and prey almost exclusively on starfish. While smaller starfish are generally the preferred prey, the species will even feed on larger species such as the Crown of Thorns Starfish (Acanthaser planci) (3). Regardless of size, the shrimps flip the starfish onto their backs and drag them back to their burrow where they clip off the tube feet, effectively immobilising their meal. From there the shrimps will continue to graze on the starfish, finally eating the heart and stomach once there is nothing left to feed on. After eating the starfish, the shrimp’s bio-accumulate the poisons in their prey’s body and use it in their own defence.

Harlequin Shrimp pair up for life, working together in both wild and captivity, to take down larger prey and defend against predators. Females are larger than the males, and have more brightly coloured abdominal plates. The female shrimp will, depending on the environmental conditions, lay up to 100 to 5,000 eggs, which upon hatching emerge as miniature adults, completely skipping the larval form.

Nature’s Most Wanted #2 Chinese Mitten Crab

The Chinese Mitten Crab (Eriocheir sinensis) is a stocky crab with a carapace width of 5 to 7cm, and has a hair like covering on its claws. The species inhabits brackish water, rivers and lakes across its native range of China, and its invasive range across Europe and North America (4). While the species is predatory, and feeds on fish eggs, the real damage that the crab does is to river banks when it burrows.

The knock of effect of the crabs removing sediment, is that it can facilitate the collapse of river banks, and in man-made levees cause the weakening or destruction of flood defences. In addition the crab has a habit of crawling into existing holes, including water intake valves and filtration drains in fish farms. Mitten Crabs are also the secondary host of the human lung fluke worm (Paragonimus westermanii) in its native range across Asia, and could potentially spread it into European waters.

Since their introduction to German waters in 1912, the Chinese Mitten Crab has caused over 80 million euros of damage to infrastructure and fish stocks. Schemes such as ‘catch as many as you can’ has limited success, as have nets and electric screens fixed to the bottom of the river in the 30s and 40s. In addition awareness of the species destructive habitats have gone unannounced, with some across its invasive range assuming the species is native to the rivers and lakes of Europe. In some areas, such as the United Kingdom, there has been talk of large scale commercial fishing schemes, yet so far nothing has been implemented yet.

References

1. www.arkive.org

2. http://www.waquarium.org/_library/images/education/marinelifeprofiles/harlequinshrimp0909.pdf

3. Glen, P.W, Interactions between Acanthaster and Hymenocera in the field and laboratory. In: D.L. Taylor (ed.) Proceedings of Third International Coral Reef Symposium Vol. 1: Biology. Rosenstiel School of Marine and Atmospheric Science, Miami, Florida. pp. 209-216. 1977

4. http://www.issg.org/database/species/ecology.asp?si=38&fr=1&sts=&lang=EN

Picture References

1. https://blog.primescuba.com/wp-content/uploads/2015/04/harlequin.jpg

2. http://www.wildlifeextra.com/resources/listimg/whales/marine_2009/yan_harlequin_shrimp@body2.JPG

3. http://farm3.staticflickr.com/2512/4039085349_818784db27_z.jpg

And that’s the terrible harlequin shrimp and its cruel and deadly starfish killing tactics. Next week we have a leaf munching request from @quinnofthestoneage, but until then remember to critic, comment and discuss future species to cover as well as checking out past issues in Impurest’s Bestiary.

Many Thanks

Impurest Cheese