RESUMO

Land flatworms are carnivorous, mainly predators. However, knowledge on their predatory behavior and prey preference is very scarce. This paucity of data is a limiting factor in the study of their biology and organismal ecology, resulting in a very difficult task to breed them in the laboratory for prolonged periods if prey preference and predation frequency are unknown. We investigated the predatory behavior of Notogynaphallia abundans (Graff, 1899), Geoplaninae, based on laboratory experiments. In order to determine its predatory choices, we offered mollusks, earthworms, arthropods, and other land flatworms. Only land isopods were accepted, with an average consumption of 3.4 individuals per week. Linear regression showed a positive relationship between the number of consumed isopods and the increase/decrease in body mass. Consumption resulting in an increase in body mass was ca. four isopods per week. Predatory behavior, with a mean time-span of 28 min 45 s ± 15 min 47 s, includes encounter and capture of prey, immobilization, handling and feeding. Variation in the duration of this activity in N. abundans is clearly due to variations in the time necessary for transferring the prey from either the anterior or posterior thirds of the body to the mouth, as well as for external digestion and ingestion. In order to capture very active and fast-moving animals such as land isopods, N. abundans employs various strategies, using either the anterior or the posterior body regions to press the prey against the ground or against its own body, thus allowing it to deal with various responses by the prey, and thereby maximizing predatory success. Similar to other flatworms, both physical holding and entrapment in a mucous secretion are of fundamental importance for prey-immobilization. The different strategies employed by land flatworms in their predatory behavior are discussed, and behavioral plasticity in the capture and immobilization of prey in different platyhelminth groups is emphasized.

RESUMO

Land flatworms are carnivorous, mainly predators. However, knowledge on their predatory behavior and prey preference is very scarce. This paucity of data is a limiting factor in the study of their biology and organismal ecology, resulting in a very difficult task to breed them in the laboratory for prolonged periods if prey preference and predation frequency are unknown. We investigated the predatory behavior of Notogynaphallia abundans (Graff, 1899), Geoplaninae, based on laboratory experiments. In order to determine its predatory choices, we offered mollusks, earthworms, arthropods, and other land flatworms. Only land isopods were accepted, with an average consumption of 3.4 individuals per week. Linear regression showed a positive relationship between the number of consumed isopods and the increase/decrease in body mass. Consumption resulting in an increase in body mass was ca. four isopods per week. Predatory behavior, with a mean time-span of 28 min 45 s ± 15 min 47 s, includes encounter and capture of prey, immobilization, handling and feeding. Variation in the duration of this activity in N. abundans is clearly due to variations in the time necessary for transferring the prey from either the anterior or posterior thirds of the body to the mouth, as well as for external digestion and ingestion. In order to capture very active and fast-moving animals such as land isopods, N. abundans employs various strategies, using either the anterior or the posterior body regions to press the prey against the ground or against its own body, thus allowing it to deal with various responses by the prey, and thereby maximizing predatory success. Similar to other flatworms, both physical holding and entrapment in a mucous secretion are of fundamental importance for prey-immobilization. The different strategies employed by land flatworms in their predatory behavior are discussed, and behavioral plasticity in the capture and immobilization of prey in different platyhelminth groups is emphasized.

RESUMO

Land flatworms are carnivorous, mainly predators. However, knowledge on their predatory behavior and prey preference is very scarce. This paucity of data is a limiting factor in the study of their biology and organismal ecology, resulting in a very difficult task to breed them in the laboratory for prolonged periods if prey preference and predation frequency are unknown. We investigated the predatory behavior of Notogynaphallia abundans (Graff, 1899), Geoplaninae, based on laboratory experiments. In order to determine its predatory choices, we offered mollusks, earthworms, arthropods, and other land flatworms. Only land isopods were accepted, with an average consumption of 3.4 individuals per week. Linear regression showed a positive relationship between the number of consumed isopods and the increase/decrease in body mass. Consumption resulting in an increase in body mass was ca. four isopods per week. Predatory behavior, with a mean time-span of 28 min 45 s ± 15 min 47 s, includes encounter and capture of prey, immobilization, handling and feeding. Variation in the duration of this activity in N. abundans is clearly due to variations in the time necessary for transferring the prey from either the anterior or posterior thirds of the body to the mouth, as well as for external digestion and ingestion. In order to capture very active and fast-moving animals such as land isopods, N. abundans employs various strategies, using either the anterior or the posterior body regions to press the prey against the ground or against its own body, thus allowing it to deal with various responses by the prey, and thereby maximizing predatory success. Similar to other flatworms, both physical holding and entrapment in a mucous secretion are of fundamental importance for prey-immobilization. The different strategies employed by land flatworms in their predatory behavior are discussed, and behavioral plasticity in the capture and immobilization of prey in different platyhelminth groups is emphasized.

RESUMO

Land flatworms are carnivorous, mainly predators. However, knowledge on their predatory behavior and prey preference is very scarce. This paucity of data is a limiting factor in the study of their biology and organismal ecology, resulting in a very difficult task to breed them in the laboratory for prolonged periods if prey preference and predation frequency are unknown. We investigated the predatory behavior of Notogynaphallia abundans (Graff, 1899), Geoplaninae, based on laboratory experiments. In order to determine its predatory choices, we offered mollusks, earthworms, arthropods, and other land flatworms. Only land isopods were accepted, with an average consumption of 3.4 individuals per week. Linear regression showed a positive relationship between the number of consumed isopods and the increase/decrease in body mass. Consumption resulting in an increase in body mass was ca. four isopods per week. Predatory behavior, with a mean time-span of 28 min 45 s ± 15 min 47 s, includes encounter and capture of prey, immobilization, handling and feeding. Variation in the duration of this activity in N. abundans is clearly due to variations in the time necessary for transferring the prey from either the anterior or posterior thirds of the body to the mouth, as well as for external digestion and ingestion. In order to capture very active and fast-moving animals such as land isopods, N. abundans employs various strategies, using either the anterior or the posterior body regions to press the prey against the ground or against its own body, thus allowing it to deal with various responses by the prey, and thereby maximizing predatory success. Similar to other flatworms, both physical holding and entrapment in a mucous secretion are of fundamental importance for prey-immobilization. The different strategies employed by land flatworms in their predatory behavior are discussed, and behavioral plasticity in the capture and immobilization of prey in different platyhelminth groups is emphasized.

RESUMO

Land flatworms are carnivorous, mainly predators. However, knowledge on their predatory behavior and prey preference is very scarce. This paucity of data is a limiting factor in the study of their biology and organismal ecology, resulting in a very difficult task to breed them in the laboratory for prolonged periods if prey preference and predation frequency are unknown. We investigated the predatory behavior of Notogynaphallia abundans (Graff, 1899), Geoplaninae, based on laboratory experiments. In order to determine its predatory choices, we offered mollusks, earthworms, arthropods, and other land flatworms. Only land isopods were accepted, with an average consumption of 3.4 individuals per week. Linear regression showed a positive relationship between the number of consumed isopods and the increase/decrease in body mass. Consumption resulting in an increase in body mass was ca. four isopods per week. Predatory behavior, with a mean time-span of 28 min 45 s ± 15 min 47 s, includes encounter and capture of prey, immobilization, handling and feeding. Variation in the duration of this activity in N. abundans is clearly due to variations in the time necessary for transferring the prey from either the anterior or posterior thirds of the body to the mouth, as well as for external digestion and ingestion. In order to capture very active and fast-moving animals such as land isopods, N. abundans employs various strategies, using either the anterior or the posterior body regions to press the prey against the ground or against its own body, thus allowing it to deal with various responses by the prey, and thereby maximizing predatory success. Similar to other flatworms, both physical holding and entrapment in a mucous secretion are of fundamental importance for prey-immobilization. The different strategies employed by land flatworms in their predatory behavior are discussed, and behavioral plasticity in the capture and immobilization of prey in different platyhelminth groups is emphasized.

RESUMO

The National Park of Aparados da Serra (PNAS), located at the Eastern border of Araucarian Plateau, is one of the main protected areas of Southern Brazil, being characterized by the occurrence of fragments of mixed ombrophilous forest, surrounded by wet and dry grassland fields, and a continuous area of dense ombrophilous forest. We registered for the PNAS 35 species of land planarians, distributed into five genera (Geoplana Stimpson, 1857, Choeradoplana Graff, 1896, Notogynaphallia Ogren & Kawakatsu, 1990, Pasipha Ogren & Kawakatsu, 1990 and Cephaloflexa Carbayo & Leal-Zanchet, 2003) of the family Geoplanidae, subfamily Geoplaninae. We observed 23 and 21 species, respectively, in the areas of mixed ombrophilous forest and dense ombrophilous forest. The Jaccard's similarity coefficient between the two areas was 0.42. In areas of dry grassland field, only one species was observed. Seven species were collected in disturbed open habitats, four of them also observed in the forest areas. The known distribution of four species, i.e., Cephaloflexa bergi (Graff, 1899), Notogynaphallia graffi Leal-Zanchet & Froehlich, 2006, Geoplana franciscana Leal-Zanchet & Carbayo, 2001, and Geoplana josefi Carbayo & Leal-Zanchet, 2001, the two latter ones having been known only from their type-locality, is amplified.

O Parque Nacional dos Aparados da Serra (PNAS), localizado na borda oriental do Planalto das Araucárias, é uma das principais unidades de conservação do sul do Brasil, caracterizando-se pela ocorrência de fragmentos de floresta ombrófila mista, intermediada por campos secos e úmidos, e por uma área contínua de floresta ombrófila densa. Registraram-se, para o PNAS, 35 espécies de planárias terrestres, distribuídas em cinco gêneros (Geoplana Stimpson, 1857, Choeradoplana Graff, 1896, Notogynaphallia Ogren & Kawakatsu, 1990, Pasipha Ogren & Kawakatsu, 1990 e Cephaloflexa Carbayo & Leal-Zanchet, 2003), pertencentes à família Geoplanidae, subfamília Geoplaninae. Observaram-se 23 e 21 espécies, respectivamente, nas áreas de floresta ombrófila mista e floresta ombrófila densa. O coeficiente de similaridade de Jaccard entre as duas formações foi de 0,42. Em áreas de campo nativo foi observada apenas uma espécie. Sete espécies foram coletadas em áreas abertas antropizadas, sendo quatro delas também observadas nas áreas de floresta. Amplia-se a distribuição de quatro espécies, a saber, Cephaloflexa bergi (Graff, 1899), Notogynaphallia graffi Leal-Zanchet & Froehlich, 2006, Geoplana franciscana Leal-Zanchet & Carbayo, 2001, e Geoplana josefi Carbayo & Leal-Zanchet, 2001, as duas últimas conhecidas somente da sua localidade-tipo.

RESUMO

The National Park of Aparados da Serra (PNAS), located at the Eastern border of Araucarian Plateau, is one of the main protected areas of Southern Brazil, being characterized by the occurrence of fragments of mixed ombrophilous forest, surrounded by wet and dry grassland fields, and a continuous area of dense ombrophilous forest. We registered for the PNAS 35 species of land planarians, distributed into five genera (Geoplana Stimpson, 1857, Choeradoplana Graff, 1896, Notogynaphallia Ogren & Kawakatsu, 1990, Pasipha Ogren & Kawakatsu, 1990 and Cephaloflexa Carbayo & Leal-Zanchet, 2003) of the family Geoplanidae, subfamily Geoplaninae. We observed 23 and 21 species, respectively, in the areas of mixed ombrophilous forest and dense ombrophilous forest. The Jaccard's similarity coefficient between the two areas was 0.42. In areas of dry grassland field, only one species was observed. Seven species were collected in disturbed open habitats, four of them also observed in the forest areas. The known distribution of four species, i.e., Cephaloflexa bergi (Graff, 1899), Notogynaphallia graffi Leal-Zanchet & Froehlich, 2006, Geoplana franciscana Leal-Zanchet & Carbayo, 2001, and Geoplana josefi Carbayo & Leal-Zanchet, 2001, the two latter ones having been known only from their type-locality, is amplified.

O Parque Nacional dos Aparados da Serra (PNAS), localizado na borda oriental do Planalto das Araucárias, é uma das principais unidades de conservação do sul do Brasil, caracterizando-se pela ocorrência de fragmentos de floresta ombrófila mista, intermediada por campos secos e úmidos, e por uma área contínua de floresta ombrófila densa. Registraram-se, para o PNAS, 35 espécies de planárias terrestres, distribuídas em cinco gêneros (Geoplana Stimpson, 1857, Choeradoplana Graff, 1896, Notogynaphallia Ogren & Kawakatsu, 1990, Pasipha Ogren & Kawakatsu, 1990 e Cephaloflexa Carbayo & Leal-Zanchet, 2003), pertencentes à família Geoplanidae, subfamília Geoplaninae. Observaram-se 23 e 21 espécies, respectivamente, nas áreas de floresta ombrófila mista e floresta ombrófila densa. O coeficiente de similaridade de Jaccard entre as duas formações foi de 0,42. Em áreas de campo nativo foi observada apenas uma espécie. Sete espécies foram coletadas em áreas abertas antropizadas, sendo quatro delas também observadas nas áreas de floresta. Amplia-se a distribuição de quatro espécies, a saber, Cephaloflexa bergi (Graff, 1899), Notogynaphallia graffi Leal-Zanchet & Froehlich, 2006, Geoplana franciscana Leal-Zanchet & Carbayo, 2001, e Geoplana josefi Carbayo & Leal-Zanchet, 2001, as duas últimas conhecidas somente da sua localidade-tipo.