167. ANIMALS FIXED TO THE EARTH LIKE PLANTS: Sponges Rooted to the Sea-floor.

[There is one division that consists of] animals that remain perfectly fixed to the bottom or are capable only of creeping or crawling over the rocks and sand, such as the sponges, hydroids, sedentary tunicates, gasteropods, most lamellibranchs, and many crustacea. This portion of the fauna [of the sea] has been called the benthos.

— HICKSON Fauna of the Deep Sea, ch. 3, p. 53. (A., 1894.) 



Meiofauna (medium [sized] fauna) are small invertebrates that live either at the bottom of a body of water (“epifauna”) or just below it, burrowed into the sediment (“infauna”). There are both marine and freshwater meiofauna.

The term Meiofauna is not taxonomic. It’s a way of grouping bottom dwelling organisms by their size: larger than microfauna but smaller than macrofauna. In the field this means they can pass through a 1 mm mesh but will be retained by a 45 μm mesh, [Wikipedia]


[1] Darkfield photograph of a gastrotrich. Taken through a 10x ocular and 10x objective. [Source: Meiofauna of Eagle Cove] Not all gastrotrich are benthic.

[2][3] Live Ammonia tepida live benthic foraminiferan. [(2) collected from San Francisco Bay; phase-contrast photomicrograph by Scott Fay, UC Berkeley, 2005]

[4] Live planktonic foraminiferaGlobigerinella aequilateralis, from near the Bermuda Islands, showing extensive spine array, and pseudopodia running along them. [Source

[5] Example of meiofauna in Phylum Annelida: polychaete worms
[Source: Meiofauna of Eagle Cove]

[6] Example of meiofauna in Subclass Copepoda (Arthropoda: Crustacea: Maxillopoda). Copedpods are one of the most ubiquitous forms of animal life in the open ocean, but also a common component of meiofaunal communities. [Source: Meiofauna of Eagle Cove]

The giant Isopod, known scientifically as Bathynomus Giganteus, is the largest known member of the Isopod family. It is a carnivorous crustacean that spends its time scavenging the deep ocean floor. Food is extremely scarce at these great depths, so the Isopod has adapted to eat what ever happens to fall to the ocean floor from above. It will also feed on some of the small invertebrates that live at these depths.

(I can’t lie, it creeps me out. But in a good way!)

This tiny octopus weighs 45 grams on average and is smaller than your hand. It is a deep sea octopus, and this one in particular broods over its eggs for 400 days, wasting away as it feeds on itself to get energy. They live much longer than shallow water octopi as well, up to six years in some cases, rather than just one year.


Here’s some live footage of Benthos playing Memosa in Mt. Pleasant earlier this year! They’ll be playing with A Great Big Pile of Leaves, Mansions, Young Statues, and Vinacious on 3/24 at Mac’s Bar [Lansing]. This is going to be a show you won’t want to miss, so grab tickets now so you don’t forget! Fee-free tickets are available now at

Creature Feature: Spotted Wobbegong

Click to read about this weeks Creature Feature!

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In the past few posts we have discussed nocturnal shark species, or sharks that are active at night. The Spotted Wobbegong (Orectolobus maculatus)is another shark that and is endemic to Australia. Hunting in the dark of night is a good way to avoid detection by prey, but the Spotted Wobbegong has additional camouflage to help it hide. It being a “Spotted” Wobbegong, you may have guessed that…

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