Mantis Shrimp respiratory and digestive system

Respiratory system

Larger aquatic crustaceans such as mantis shrimp use modified gills for respiration. (1) However, these gills are't "true" gills, because they are found outside the body on skin-like outgrowths attached to their pleopods (hind legs adapted for swimming, swimmerets). (2,3) Oxygen diffuses into these feathered structures through their membrane as the water passes around them. The oxygen then moves from the gills into the haemolymph in the circulatory system and is distributed around the body. (1)

In mantis shrimps (order Stomatopoda) gills are found on the exopodites of the pleopods (the outer branch of pleopods)

Image from ucmp.berkeley.edu

Like all larger crustaceans, mantis shrimp have an impermeable body surface made of chitin, therefore they are unable to exchange gases by diffusion through it. Because of this, their gills have special adaptations to maximise the rate of respiration:

• pleated or double gills,

• rich vascularisation (3)

Digestive system

Mantis shrimp are carnivores, eating live soft or hard shelled invertebrates and vertebrates, often larger than themselves. (5)

Their digestive tract consists of:

• a mouth,

• a two-chambered foregut,

• a midgut with outpocketings called digestive glands (hepatopancreas) and

• a hindgut (rectum). (4)

Image via mantisshrimpsjs.weebly.com

The foregut is connected directly to the mouth, without any oesophagus and is large enough to hold remains large prey.

The second part of the stomach, pyloric stomach, lies in the posterior part of the thorax. Mainly in this part, the greatly folded and muscular stomach walls are lined with bristles, teeth and filtering setae (hair-like strucures) called the gastric mill.

The partly digested food progesses through the filtering setae into the ceca (pouches) of the hepatopancreas, where enzymes (cellulase, chitinase) are released and nutrients absorbed.

The midgut extends throughout the abdomen and fecal material leaves the bod through the rectum and anus. (4)

References:

1. Haak, D. (n.d.). Crustacean Respiratory System. [online] Study.com. Available at: https://study.com/academy/lesson/crustacean-respiratory-system.html [Accessed 28 Feb. 2019].

2. Encyclopaedia Britannica. (n.d.). Form And Function Of Internal Features. [online] Available at: https://www.britannica.com/animal/crustacean/Form-and-function-of-internal-features [Accessed 28 Feb. 2019].

3. Zapata, V. (2014). Mantis Shrimp. [online] Prezi.com. Available at: https://prezi.com/h4jpb6bnxr9j/mantis-shrimp/ [Accessed 28 Feb. 2019].

4. Conlan, K. and Bousfield, E. (n.d.). Malacostracan. [online] Encyclopaedia Britannica. Available at: https://www.britannica.com/animal/malacostracan#ref33783 [Accessed 28 Feb. 2019].

5. Ellis, C. (2017). What Do Ocean Mantis Shrimp Eat?. [online] Sciencing. Available at: https://sciencing.com/do-ocean-mantis-shrimp-eat-5468474.html [Accessed 28 Feb. 2019].