Morphology
Cristatella mucedo forms gelatinous, colourless, elongate colonies without branches or lobes that resemble a caterpillar.They form easily recognisable circular statoblasts with long, wiry, hooked spines.

Evolution
Morphological criteria suggest Cristatella mucedo and other gelatinous freshwater bryozoan species are derived within the Class Phylactolaemata.However, molecular phylogenetic analyses suggest that morphological characters have converged within this class, and this suggests a more complicated evolutionary scenario (Okuyama et al. 2006; Fuchs et al. 2009).

Genetics
The genus contains a single species. However, two genetically distinct North American lineages may represent cryptic species (Freeland 2000b).Variation in genome sizes has been recorded in North America (Potter 1979) - C-values (haploid DNA content) of 0.5 - 0.85 picograms.Karyotyping has identified 8 chromosome pairs (Potter 1979).

Look-alikes
Smaller colonies (< 10 zooids) that lack statoblasts are difficult to distinguish from Lophophodella carteri.

Cristatella mucedo is a freshwater invertebrate sometimes known as a ‘moss animal’.Individuals called zooids possess tentacle crowns for feeding and collectively form long gelatinous colonies with a soft, transparent body wall.To the naked eye undisturbed colonies are ‘fuzzy’ and caterpillar-like in appearance.Colonies are loosely attached to a substrate that might be a root, rock or manmade structure, via their muscular ‘foot’.They can ‘glide’ slowly and divide by fission.

Zooids are produced asexually by budding in linear series to either side of an interior, zooid-free stripA crown of tentacles called a lophophore extends from each zooid, These superficially contribute to the caterpillar-like appearance by resembling bristles.Colonies are loosely attached via their muscular ‘foot’ to substrates such as wood, plants or rocks and can glide slowly over the surface.Explosive growth and colony fission in early summer can result in high densities of colonies, with many hundreds of colonies deriving from initial founders (Okamura 1977; Wood & Okamura 2005).

Size
Colonies are approximately 0.5cm wide and about 2-5cm long, occasionally growing to 20cm long.Lophophores of individual zooids are about 1mm diameter.

Life cycle
Colonies of Cristatella mucedo grow from early summer and degenerate in autumn.The organism survives over winter by producing asexual seed-like statoblasts as the colony degenerates. The statoblasts remain dormant and can be dispersed by water currents and aquatic birds. They hatch in late spring to found new colonies.Sexual reproduction occurs briefly in early summer, but is not necessary for survival each year.

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Distribution
Cristatella mucedo is found in North America, the British Isles, Europe and Asia.

Habitat
It prefers still or slowly-moving waters but is otherwise broadly tolerant.Cristatella mucedo colonies have been found in recently-formed gravel pits through to well-established sites (Okamura 1997) and from oligotrophic to eutrophic conditions.Colonies are found attached to a range of natural and artificial substrata where they are protected from sedimentation – such as undersides or vertical faces.Natural substrata include

• submerged branches
• roots
• rocks
• macrophytes

Artificial substrata include

• pier pilings
• tyres
• buoys
• plastics

Cristatella mucedo Cuvier: Circum-boreal, northern hemisphere. Map in Reynolds (1976).
In Ireland, recorded from 12 lowland, alkaline locations in seven vice-counties.

Depth range based on 6 specimens in 1 taxon.
Water temperature and chemistry ranges based on 3 samples.

Environmental ranges
  Depth range (m): 8.2 - 34
  Temperature range (°C): -1.212 - -0.327
  Nitrate (umol/L): 2.397 - 2.568
  Salinity (PPS): 29.779 - 31.527
  Oxygen (ml/l): 8.300 - 8.972
  Phosphate (umol/l): 0.662 - 0.978
  Silicate (umol/l): 10.382 - 11.424

Graphical representation

Depth range (m): 8.2 - 34

Temperature range (°C): -1.212 - -0.327

Nitrate (umol/L): 2.397 - 2.568

Salinity (PPS): 29.779 - 31.527

Oxygen (ml/l): 8.300 - 8.972

Phosphate (umol/l): 0.662 - 0.978

Silicate (umol/l): 10.382 - 11.424
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Habitat Type: Freshwater

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Asexual reproduction
Statoblast dormancy is broken when favourable conditions return - light and warmth promote the release of a single zooid that establishes a new colony via budding (a form of asexual reproduction).All subsequent zooids in a colony result from budding and are genetically identical, physiologically connected modules.Asexual reproduction via colony growth, fission and statoblast production is the main mode of reproduction.

Sexual reproduction
Colonies are hermaphroditic and embryos are brooded. A ciliated larva is released and swims for a few hours before settling and metamorphosing into a small colony (Wood & Okamura 2005).Typically only a low proportion of colonies in local populations undertake sexual reproduction (Uotila & Jokela 1995; Okamura 1997). At least some larvae are products of outcrossing (Freeland et al. 2003).

Dispersal
Statoblasts have spines with hooked tips and can attach to feathers and fur (Bilton et al. 2001). They are highly resistant and achieve dispersal in time and space.Waterfowl appear to be important dispersal vectors. This is supported by:

• evidence for waterfowl-mediated gene flow (Freeland et al. 2000a; Figuerola et al. 2005)
• the presence of statoblasts in waterfowl digestive tracts (Mouronval et al. 2007)
• viability of statoblasts after passing through duck digestive tracts (Charalambidou et al. 2003)

Limited within-site dispersal is achieved by larvae, and very localised dispersal by colony movement.

Freshwater bryozoans, including Cristatella mucedo, provide a microhabitat for an ‘aufwuchs’ community of micro-organisms including:

• protozoans
• rotifers
• gastrotrichs
• microcrustaceans

(Bushnell 1966; Bushnell & Rao 1979).Larger associates appear to be predators, including

• flatworms
• leeches
• oligochaetes
• mites
• isopods
• snails
• insect larvae (trichopterans, chironomids, neuropterans)

(Wood & Okamura 2005; Weißmair 2005)Their presence is typically followed by the rapid disappearance of colonies (Okamura 1997).Midge larvae commonly build their tubes partially beneath colonies and may cause damage via their activities and occasional predation (Okamura 1997; Wood & Okamura 2005).

Nutrition
Cristatella mucedo is a suspension feeder. Food particles are captured from feeding currents created by the ciliated tentacular crown (the lophophore) (Riisgård et al. 2009).Food items are small components of the nannoplankton, especially single cells (< 7µm) with round shapes (Kamiński 1984).

Population biology
Genetic and ecological evidence indicate a metapopulation ecology - populations are ephemeral, separated geographically, and linked by gene flow

• local populations exhibit apparent extinction and recolonisation events (Okamura 1997) and large fluctuations in abundance ( Wöss 1994; Vernon et al. 1996)
• low levels of gene flow link some populations in northwest Europe
• colony genotypes occasionally misclassify to sites of non-origin (Freeland et al. 2000a,b)

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There is 1 barcode sequence available from BOLD and GenBank.   Below is the sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen.  Other sequences that do not yet meet barcode criteria may also be available.


Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 1
Specimens with Barcodes: 1
Species With Barcodes: 1

Rounded Global Status Rank: GNR - Not Yet Ranked

Canada

Rounded National Status Rank: NNR - Unranked

United States

Rounded National Status Rank: NNR - Unranked

Conservation status
C. mucedo is relatively common in freshwater bodies and there are no conservation concerns at present.