Anatomical and topographical description of the digestive system of caiman crocodilus (Linnaeus 1758), melanosuchus niger (Spix 1825) and paleosuchus palpebrosus (Cuvier 1807) / Descripción anatómica y topográfica del sistema digestivo del caimam crocodillus (Linnaeus 1758), melanosuchus niger (Spix 1825) y paleosuchus palpebrosus (Cuvier 1807)

This paper describes the digestive system of Caiman crocodilus, Melanosuchus niger and Paleosuchus palpebrosus based on anatomical and topographical inferences. The study involves two digestive systems of C. crocodilus, one of M. niger and one of P. palpebrosus, already fixed in 10 percent formaldehyde, belonging to the collection of the Wild Animal Research Laboratory (LAPAS) of the Federal University of Uberlândia. The work begins with a description of the digestive system of the aforementioned crocodilians, followed by topographical associations, aided by photographs taken with a SONY® DSC-H20 camera, X-rays of the gastrointestinal tract and a photograph of the digestive system of C. crocodilus prior to formaldehyding, which also belong to the LAPAS collection. The results indicate that the digestive system of crocodilians consists of a wide mouth, short pharynx, long straight esophagus, dilated stomach in relation to the rest of the tract, pancreas lodged between the first two ventral duodenal loops, coiled small intestine, large intestine with diameter larger than the preceding segments, and cloaca as the terminal portion of the digestive, urinary and reproductive systems. The anatomical and topographical description of the digestive system of C. crocodilus (Linnaeus, 1758) (Crocodylia: Alligatoridae), M. niger (Spix, 1825) (Crocodylia: Alligatoridae) and P. palpebrosus (Cuvier, 1807) (Crocodylia: Alligatoridae) can be extended to the other crocodilians due to interspecies and intraspecific behavioral similarities.

Mediante comparaciones anatómicas y topográficas describimos el sistema digestivo de C. crocodillus, M. nigeri y P. palpebrosus. Se utilizaron dos sistemas digestivos de C. crocodillus, uno de M. nigeri y uno de P. palpebrosus, fijados en formalina al 10 por ciento y pertenecientes al laboratorio de enseñanza e investigación de fauna silvestre (LAPAS) de la Universidade Federal de Uberlândia. En primera instancia se realizó la descripción del sistema digestivo de las mencionadas especies, seguido de comparaciones topográficas. Luego, fueron tomados registros fotográficos con cámara DSC H20 SONY. Adicional a esto, nos apoyamos con radiografías del tracto gastrointestinal y fotografías del sistema digestivo de C. crocodillus antes de ser fijados en formalina. Los resultados demuestraron que el sistema digestivo de estas tres especies de caimanes está constituido por una boca grande, faringe corta, esófago alargado y rectilíneo, estómago dilatado con relación a las otras partes del tracto digestivo, páncreas alojado entre las dos primeras curvaturas duodenales ventrales, intestino delgado plegado, intestino grueso con un diámetro mayor en relación a los segmentos anteriores y una cloaca donde también terminan los sistemas urinarios y reproductor. La descripción anatómica y topográfica del sistema digestivo de C. crocodillus, M. niger y P. palpebrosus puede ser extrapolada para otros cocodrilos por la semejanza comportamental interespecies e intraespecíficas.

A systematic study of the brain base arteries inbroad-snouted caiman (Caiman latirostris)

The objective of this study was to describe and systematize the encephalic arterial vascularization of this reptile,by providing a standard irrigation model with its major variations. Thirty broad-snouted caiman heads andtwo whole specimens were used. The arterial system was filled with red-colored latex. Only a single source ofblood supply was observed in caimans and it originated from the left aortic arch. This vessel is called the azygoscarotid artery. At the caudal base of the skull, ventral to the first cervical vertebrae, it divided into two internalcarotid arteries. The internal carotid arteries divided into a rostral branch and a short caudal branch at thehypophysis level, which continued naturally as the caudal cerebral artery. The short caudal branch gave off itsmedium-caliber portion which, gave off the mesencephalic and the ventral rostral cerebellar arteries. Then thiscaudal branch anastomosed with its contralateral counterpart, forming the basilar artery. This artery followedthe ventral median fissure of the medulla oblongata, giving off the ventral caudal cerebellar and dorsal spinalarteries, and abandoning the cranial cavity through the foramen magnum as the ventral spinal artery. Therostral branch gave off the middle cerebral, rostral cerebral and rostral communicating arteries. The middlecerebral artery arose from a network originated from one to five collateral branches of the rostral branch of theinternal carotid artery. It was observed that the cerebral arterial circle was rostrally and caudally closed and,therefore, the cerebral blood supply was exclusively made by the carotid system.

Description of embryonic stages in Melanosuchus niger(Spix, 1825) (Crocodylia: Alligatoridae)

The determination of embryonic stages is very useful in comparative and evolutionary anatomy, experimentalresearch and ecological studies. Although tables of development stages already exist for some crocodilianspecies, no table has yet been published for Melanosuchus niger. Therefore, the aim of this work is to monitorthe development of this species of Alligatoridae and characterize its stages based on the main morphologicaltransformations the embryo undergoes during the incubation process. Under natural conditions, two sampleswere collected daily in the Lake Cuniã Extractive Reserve in Rondônia, Brazil, making a total of 186 eggs.The incubation period was 90 days at an ambient temperature varying from 25.2 to 31.7 °C. We established24 embryonic stages between the formation of the pharyngeal arch and hatching. Primordia for the sensoryorgans and somites were observed in the early stages. The buds of the pelvic and thoracic limbs emergedsimultaneously, also in the early stages. An analysis of these structures showed evidence of considerableevolutionary modifications when compared with embryos of different species. In stage 12 we observed subtlepigmentation in the region of the head and, in stage 25, the pigmentation and striped pattern were typical ofthe newly hatched specimen. The eyetooth was visible in stage 18, disappearing within the first few weeks afterhatching. The vitellus was completely absorbed in the penultimate stage. Direct comparisons of the table ofembryonic stages were made between M. niger and other crocodilian taxa, and the main differences identifiedwere chronological variations.

Crecimiento del caimán del Orinoco (Crocodylus intermedius, Crocodylia: Crocodylidae) en dos condiciones de cautiverio / Growth of the Orinoco Caiman (Crocodylus intermedius, Crocodylia: Crocodylidae) under two captivity conditions

Growth of the Orinoco Caiman (Crocodylus intermedius, Crocodylia: Crocodylidae) under two captivity conditions. In order to determine the growth of Caiman of the Orinoco (Crocodylus intermedius) under two conditions of captivity, 40 specimens were raised during 11 months and 15 days in two circular tanks, with 28.3 m2 of surface area and a volume of 62.2 m3 in each tank. The tanks were built with concrete walls and guarded blocks covered internally with sheets of myrrhlike resin, and a roof of galvanized sheets. One tank was covered partially with the galvanized sheets (tank I), the other was totally covered (tank II). Twenty caimans were placed in each tank, and both groups were fed with 85% beef, 10% fresh fish, 5% hen eggs and a mixture of minerals and vitamins. The length and weight differed significantly between the groups (p < 0.001). Mean growth (103.0 +/- 6.81 cm) and weight (3 987 +/- 0.98 g) were higher in tank II, (tank I: 88.9 +/- 7.58 cm; 2 705 +/- 0.69 g). The greater growth in tank II reflects higher air and water temperatures. The survival rate was 97.5%. These results can be used for rearing caimans in captivity for conservation and commercial purposes.

para determinar el crecimiento del caimán del Orinoco (Crocodylus intermedius), en diferentes condiciones de cautiverio, se criaron 40 ejemplares durante 11 meses y 15 días. Se utilizaron dos tanques circulares, con una superficie de 28.3 m2 y un volumen de 62.2 m3, construidos con bloques de concreto y protegidos con techo de láminas galvanizadas e internamente cubiertos con láminas de resina. Un tanque fue cubierto parcialmente con láminas galvanizadas (Tanque I) y el otro se techó totalmente (Tanque II). Se colocaron 20 cocodrilos en cada tanque y a los dos grupos se les administró una dieta compuesta por 85% de carne de res, 10% de carne de pescado, 5% de huevos de gallina y mezcla de minerales y vitaminas. El crecimiento en longitud total y peso difirió entre grupos (p < 0.001). Los cocodrilos del tanque II obtuvieron un mayor crecimiento promedio en longitud total (103.0 ± 6.81 cm) y peso (3 987 ± 0.98 g). En el tanque los valores fueron 88.9 ± 7.58 cm; y 2 705 ± 0.69 g. El mayor crecimiento en el tanque II se debió a mayores niveles de temperatura del aire y del agua. La tasa de supervivencia fue 97.5%. La investigación demostró la factibilidad de criar cocodrilos en estas condiciones de cautiverio para la conservación y para propósitos comerciales.

Growth of broad-nosed caiman, Caiman latirostris (Daudin, 1802) hatchlings, fed with diets of animal origin

The study was carried out to evaluate the growth rate of broad-nosed caiman, Caiman latirostris hatchlings, fed on four animal protein diets: (a) dead poultry from a poultry farm; (b) dead piglet from nursery and farrowing house in a swine farm; (c) whole tilapia (Tilapia rendalli e Oreochromis niloticus); and (d) a balanced mixture of a, b, and c sources. Sixteen seven-month old caimans, average weight of 208 g and, 38 cm of total lenght (TL) were distributed in four treatments. Four groups of four caimans each were placed in cement enclosures inside a greenhouse. Diets were supplied at the average rate of 97.8 percent ± 34.8 percent of the body weight per week (average and standard deviation; wet weight basis). Body mass and total length of caimans were measured every 30 days for six months (Nov. 1995-April. 1996). An analysis of variance with repeated measures was performed. Diets provided suitable growth for weight and TL (mean ± standard deviation, respectively): (a) 2,157 ± 743 g and 79.5 ± 6.9 cm; (b) 1,811 ± 222 g and 75.7 ± 1.9 cm; (c) 2,431 ± 780 g and 80.7 ± 5.8 cm; (d) 1,683.5 ± 736 g and 74.5 ± 7.2 cm. There was no significant effect of diet on weight, but diet effect on TL of hatchlings approached significance (p < 0.10). It is concluded that all diets have good potential, in growth sense, to be used in commercial farms or ranches and for captivity propagation programs of caimans