Lubomirskiidae is a family of freshwater sponges from

Lake Baikal Lake Baikal is a rift lake and the deepest lake in the world. It is situated in southern Siberia, Russia between the Federal subjects of Russia, federal subjects of Irkutsk Oblast, Irkutsk Oblasts of Russia, Oblast to the northwest and the Repu ...

in Russia,

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the lake, though there are unconfirmed reports from Lake Jegetai-Kul in the Western Sayan, along with the

Bering Sea The Bering Sea ( , ; rus, Бе́рингово мо́ре, r=Béringovo móre, p=ˈbʲerʲɪnɡəvə ˈmorʲe) is a marginal sea of the Northern Pacific Ocean. It forms, along with the Bering Strait, the divide between the two largest landmasse ...

and the sea surrounding

Kamchatka The Kamchatka Peninsula (, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and western coastlines, respectively. Immediately offshore along the Pacific ...

Description

Lubomirskia baikalensis ''Lubomirskia baikalensis'' is a freshwater species of sponge that is endemic to Lake Baikal, Russia. It is commonly called the Lake Baikal sponge and it is the most abundant sponge in the lake, but all the approximately 15 species of sponges in ...

'' (the most abundant species), '' Baikalospongia bacillifera'' and '' B. intermedia'' are unusually large for freshwater sponges and can reach or more.Kaluzhnaya; Belikov; Schröder; Rothenberger; Zapf; Kaandorp; Borejko; Müller; and Müller (2005). ''Dynamics of skeleton formation in the Lake Baikal sponge Lubomirskia baicalensis. Part I. Biological and biochemical studies.'' Naturwissenschaften 92: 128–133. These three are also the most common sponges in Lake Baikal. Lubomirskiid sponges are

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

, and may grow in multiple ways; they may encrust their

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...

( cortical growth), or grow up into either a form low to the substrate (

cushion A cushion is a soft bag of some ornamental material, usually stuffed with wool, hair, feathers, polyester staple fiber, non-woven material, cotton, or even paper torn into fragments. It may be used for sitting or kneeling upon, or to soften ...

-shaped) or a tall

branch A branch, also called a ramus in botany, is a stem that grows off from another stem, or when structures like veins in leaves are divided into smaller veins. History and etymology In Old English, there are numerous words for branch, includ ...

ing one. Growth is slow, around per year. Their skeleton is typically "multispicular

alveolate The alveolates (meaning "pitted like a honeycomb") are a group of protists, considered a major unranked clade or superphylum within Eukaryota. They are currently grouped with the Stramenopiles and Rhizaria among the protists with tubulocristate ...

reticulate Reticulation is a net-like pattern, arrangement, or structure. Reticulation or Reticulated may refer to: * Reticulation (single-access key), a structure of an identification tree, where there are several possible routes to a correct identificati ...

". Their megasclere spicules consist of spiny oxeas and strongyles, and they do not develop microscleres. Spongin is present throughout their body, such as the tips of their spicules, though this

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

may be absent in some parts of the body. Going through a grade of ''Lubomirskia''-''Baikalospongia''-''Swartschewskia'', the ectosomal skeleton ranges from "tufts" of spicule "from the primary fibres" to "hard and well-developed", while the choanosomal skeleton ranges from regularly

anisotropic Anisotropy () is the structural property of non-uniformity in different directions, as opposed to isotropy. An anisotropic object or pattern has properties that differ according to direction of measurement. For example, many materials exhibit ver ...

to "sparsely developed". Using this same grade, the

consistency In deductive logic, a consistent theory is one that does not lead to a logical contradiction. A theory T is consistent if there is no formula \varphi such that both \varphi and its negation \lnot\varphi are elements of the set of consequences ...

of the sponge's body ranges from elastic to fragile, though individuals of all species range from rigid to soft or

flabby Obesity is a medical condition, considered by multiple organizations to be a disease, in which excess body fat has accumulated to such an extent that it can potentially have negative effects on health. People are classified as obese when ...

. Lubomirskiidae is endemic to Lake Baikal, being commonly found throughout the lake from depths of , though the various species have optimal

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

ranges where they can become abundant and dominate the ecosystem. Some species, such as '' L. abietina'', '' B. martisoni'', and '' B. fungiformis'', have wide depth ranges; they are recorded close to the surface ( deep respectively) and down in the "

abyssal zone The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. The word ''abyss'' comes from the Greek word (), meaning "bottomless". At depths of , this zone remains in perpetual darkness. It covers 83% of the total area ...

" of the lake ( deep respectively). This family lacks the gemmules characteristic of Spongillids, which restricts them to

sexual reproduction Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote tha ...

; along with their reliance on larval dispersal, this reproductive cycle is thought to have restricted them, along with fellow Spongillid families Malawispongiidae and Metschnikowiidae, within the ancient hydrographic basins and

waterway A waterway is any Navigability, navigable body of water. Broad distinctions are useful to avoid ambiguity, and disambiguation will be of varying importance depending on the nuance of the equivalent word in other ways. A first distinction is ...

s that they are native to. As typical of sponges in general, Lubomirskiids are

filter feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a s ...

s, which may make them useful as

bioindicator A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...

s of heavy metal pollution. Most sponges in the lake are typically green when alive because of

photosynthetic Photosynthesis ( ) is a Biological system, system of biological processes by which Photoautotrophism, photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical ener ...

microorganisms which

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

ally live within their tissues ( zoochlorella, both

dinoflagellate The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...

s and

Chlorophyta Chlorophyta is a division of green algae informally called chlorophytes. Description Chlorophytes are eukaryotic organisms composed of cells with a variety of coverings or walls, and usually a single green chloroplast in each cell. They are ...

), but can also be brownish or yellowish. In 2011, cases of discolored sponges were first reported, where some stands would acquire a "dirty pink" color; these "bleached" sponges (similar to

coral bleaching Coral bleaching is the process when corals become white due to loss of Symbiosis, symbiotic algae and Photosynthesis, photosynthetic pigments. This loss of pigment can be caused by various stressors, such as changes in water temperature, light, ...

) experience a shift in their

microbiome A microbiome () is the community of microorganisms that can usually be found living together in any given habitat. It was defined more precisely in 1988 by Whipps ''et al.'' as "a characteristic microbial community occupying a reasonably wel ...

; an increase in

cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

numbers is often observed. This bleaching disease risks the health of the sponge population in the lake as the Chlorophyta experience mass death, with the diseased sponges eventually undergoing

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. The term "necrosis" came about in the mid-19th century and is commonly attributed to German pathologist Rudolf Virchow, who i ...

. The death of sponges would affect the community of sponges and eventually the entire ecosystem of the lake itself.

Genera and species

The family contains four genera and sixteen species. The different genera are distinguished by the characters of their megascleres, though

molecular analysis Genetic testing, also known as DNA testing, is used to identify changes in DNA sequence or chromosome structure. Genetic testing can also include measuring the results of genetic changes, such as RNA analysis as an output of gene expression, or ...

may be more reliable as megasclere character states overlap between species and genera. Microsatellite markers may be the most reliable method of determining the

phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

of these sponges. A number of phylogenetic analyses have been made to elaborate on the interrelationships of Lubomirskiidae; with some recent analyses having recovered the

polyphyly A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as homoplasies, which ar ...

of ''Baikalospongia''.

References

External links

Pictures of live sponges and spicules
{{Taxonbar, from=Q4117876 Sponge families Heteroscleromorpha Fauna of Lake Baikal