![if an animal s described as fossorial if an animal s described as fossorial](https://i.natgeofe.com/n/e0737edc-f821-46b8-bc68-3f6b523510bc/docofossor1_2x3.jpg)
The spatial distribution of the openings showed a significant fit to the Negative Binomial distribution, indicating that the distribution of the openings is aggregated, as confirmed from the burrow morphology. The soil with burrows had higher percentages of coarse sand, fine sand, and silt. The water was hypoxic and slightly acidic, and the dissolved oxygen content was very low (mean 1.43 mg/l) (18.2% saturation). defossus, the water temperature ranged between 16.6☌ (autumn 2004) and 23☌ (spring 2003). The adult population density was estimated by direct observation of burrows and counts in the study area. To estimate the spatial distribution of the openings, the observed distribution was compared with the expected distribution predicted by the Poisson and Negative Binomial frequency-distribution models. The spatial distribution and changes in the number and shape of the surface openings over time were observed in a 100 m 2 area. Burrow morphology was analyzed by means of resin and gypsum casts. Environmental measurements (temperature, pH, dissolved oxygen, and water-table depth) of the water in the galleries were made monthly. The present field study was carried out in Lami, Porto Alegre, Rio Grande do Sul, Brazil, from May 2003 through August 2005. E-mail: defossus Faxon, 1898 is a fossorial crayfish species, which constructs its burrows in swampy areas in southeast Uruguay and in the state of Rio Grande do Sul, Brazil. Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal do Rio Grande do Sul. From knowledge of the burrow morphology, the population density was estimated to be about 120 individuals/100 m².
![if an animal s described as fossorial if an animal s described as fossorial](https://media.nationalgeographic.org/assets/photos/000/309/30993_c0-33-990-710_r380x260.jpg)
The galleries are always formed by a central tunnel with multiple branchings that connect the underground water to the soil surface by one or more openings, which can be recognized by the chimneys. The spatial distribution and changes in the number and shape of the surface openings over time were observed in a 100 m² area.
![if an animal s described as fossorial if an animal s described as fossorial](https://dfzljdn9uc3pi.cloudfront.net/2020/9934/1/fig-5-full.png)
![if an animal s described as fossorial if an animal s described as fossorial](https://www.researchgate.net/profile/Hornung-Elisabeth/publication/334381171/figure/fig1/AS:781068718325760@1563232702555/Maximum-dispersal-ranges-for-the-movement-of-animal-groups-for-which-evidence-of.png)
Parastacus defossus Faxon, 1898 is a fossorial crayfish species, which constructs its burrows in swampy areas in southeast Uruguay and in the state of Rio Grande do Sul, Brazil.