This is a Bryozoan statoblast. It is a cyst that can survive over the winter and begin a new Bryozoan colony when conditions permit. The little anchor shaped hooks really cling to things and allow the statoblast to hitch a ride on vegatation or animals. ” Photos by Charles Krebs


Bryozoan Statoblast (diminutive aquatic animal of the phylum Bryozoa) (10x)

“Survival pod” of a bryozoan colony:

“Phylactolaemates also reproduce asexually by a method that enables a colony’s lineage to survive the variable and uncertain conditions of freshwater environments.[16] Throughout summer and autumn they produce disc-shaped statoblasts, masses of cells that function as “survival pods” rather like the gemmules of sponges.[6] Statoblasts form on the funiculus connected to the parent’s gut, which nourishes them.[16] As they grow, statoblasts develop protective bivalve-like shells made of chitin. When they mature, some statoblasts stick to the parent colony, some fall to the bottom (“sessoblasts”), some contain air spaces that enable them to float (“floatoblasts”),[6] and some remain in the parent’s cystid to re-build the colony if it dies.[16] Statoblasts can remain dormant for considerable periods, and while dormant can survive harsh conditions such as freezing and desiccation. They can be transported across long distances by animals, floating vegetation, currents[6] and winds,[16] and even in the guts of larger animals.[64] When conditions improve, the valves of the shell separate and the cells inside develop into a zooid that tries to form a new colony. Plumatella emarginata produces both “sessoblasts”, which enable the lineage to control a good territory even if hard times decimate the parent colonies, and “floatoblasts”, which spread to new sites. New colonies of Plumatella repens produce mainly “sessoblasts” while mature ones switch to “floatoblasts”.[61] A study estimated that one group of colonies in a patch measuring 1 square metre (11 sq ft) produced 800,000 statoblasts.[6]

Terrifying (but tiny!) bryozoans

Images 1 and 2: Beania mirabilis (source) cc-by-nc-sa

Image 3: Electra monostachys (source) cc-by-nc-sa

Image 1: “Scanning electron microscope image of a bryozoan colony” (Source)

Image 2: “This skeleton of a living bryozoan, collected at Bahia de los Angeles, Baja California, clearly shows this typical colonial organiation.

Each individual, or zooid, is enclosed in a sheath of tissue, the zooecium, that in many species secretes a rigid skeleton of calcium carbonate. Each zooid in this electron micrograph is less than a millimeter long and has a single opening, the orifice. Through this opening, the lophophore, a ring of ciliated tentacles centered on the mouth, protrudes to capture small food particles. The lophophore can be retracted very rapidly by specialized retractor muscles, and the opening closed by a doorlike operculum, visible on some of the zooids in the picture at the left.”


Image 3: Membraniporella nitida (source) cc-by-nc-sa

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