African Land Snail Research Articles

Seasonal variation in the biochemical composition of the albumen gland of the giant African land snail Archachatina marginata in Abeokuta, Ogun State, Nigeria

ABSTRACT Archachatina marginata is an African pulmonate gastropod widely reared for food. There is a lack of information on the influence of seasonal changes on the reproductive physiology of these snails, hindering optimum reproduction throughout the year. Thus, the aim of this study was to measure seasonal variation in the albumen gland of A. marginata snails in Abeokuta, Ogun State, Nigeria. A total of 252 snails was purchased from the Department of Forestry and Wildlife Management of Federal University of Agriculture, Abeokuta, Ogun State, Nigeria. The snails were acclimatised for three weeks in rearing cages. Twenty-one snails were dissected each month for twelve months and the albumen gland separated. Samples collected were analysed in the laboratory using standard chemical methods. Data collected were analysed using one-way analysis of variance and t-test. Glucose (P < 0.05) and protein (non-significant) were found to be higher in the dry season than in the rainy season, while cholesterol (P < 0.05) and triacylglycerol (non-significant) were higher in the rainy season than in the dry. In conclusion, this study showed that the biochemical composition of the albumen gland of A. marginata snails was influenced by seasonal variation.

Mild histological distortions in rat organs after a 14-day oral exposure to the slime extract of African giant land snails

ObjectiveSnail slime possesses various pharmacological activities that are becoming attractive for zootherapy, thereby necessitating the profiling of its safety and toxicity. Therefore, using OECD 425 guidelines, this study assessed the acute toxicity of Archachatina marginata slime extract and performed a histological analysis of the vital organs. MethodsEighteen (18) Wistar rats were assigned randomly into three groups: control, 2000 mg/kg, and 5000 mg/kg bw slime extract. The dosing of the animals with 2000 mg/kg bw and 5000 mg/kg bw was done according to the limit test procedure, after which the animals were observed for 14 days. During the observation period, clinical and behavioral changes were recorded. The rats were euthanized after 14 days of monitoring, and their essential organs were excised for gross histological examination. ResultsThere was no mortality during the observation period, and the LD50 of A. marginata slime extract was determined to be greater than 5000 mg/kg bw. Although there were no behavioral alterations in the rats after oral exposure to the slime extract, the histological examination revealed mild cellular distortions in the rat organs. Furthermore, a preliminary chemical analysis of the slime extract revealed the presence of flavonoids and phenolics. ConclusionA. marginata slime extracts may be grouped as low toxic substance based on the results obtained (LD50 > 2000 – 5000 mg/kg). However, the histological distortions in rat organs following acute oral exposure to the snail slime extract not only warrant further, in-depth toxicological investigations but also caution in its use for traditional medicinal purposes.

High resolution stable isotope ratios in modern African land snails: Testing inferred environmental conditions

High-resolution sub-annual stable oxygen isotope data were measured in modern land snail shells collected from different climatic zones in Africa to search for patterns in seasonal δ18O cycles associated with specific hydroclimates, keyed to flora/biozones. Thirty-three recently dead shells were collected between 1995 and 2012, and collection localities were divided into five climate types: tropical forest, woodland savannah, bushland savannah, woodland monsoon, and arid/semi-arid. Thirteen genera are represented in the collection. Sampling covered at least one year in the life of the land snails, often multiple years. A comparison of measured data to predicted δ18O values, using local temperature and rain δ18O value, shows that predictions tend to be lower than measured values, suggesting that surface waters or snail body waters have undergone some evaporation. Predictions based on night-time temperatures (average monthly minimum T) are closer to, but still underestimate, measured values compared to day-time (maximum) temperatures in a majority of cases. The largest range in δ18O values for individual shells occurs in the bushland savannah and woodland monsoon biomes. Longer seasonal intervals of dry conditions lead to greater δ18O ranges in shells, although if the dry interval approaches 10 months in the year the amplitude is again reduced. This is in agreement with other oxygen isotope studies of high-resolution land snail shell samples, which show very high δ18O variance in strong monsoon climates.

Trade and socioeconomic importance of an invasive giant snail in the endemic-rich island of São Tomé, Central Africa.

Managing invasive species is crucial to mitigate their negative impacts on ecosystems, yet conflicts may arise when their social benefits are disregarded. Human pressure on the endemic-rich forests of São Tomé has been high since the island was discovered by the Portuguese in the 15th century, and numerous species have been introduced. These include the invasive West African giant land snail (Archachatina marginata), which was introduced in the mid-20th century, is now widespread on the island, and is a potential threat to native flora and fauna. We assessed the frequency of consumption of this species and its socioeconomic importance to people across the island with household questionnaires, focus group discussions, and semistructured interviews. We explored the prevalence and potential drivers of use (e.g., wealth, household composition, and diversity of occupations) and characterized the commodity chain to identify demographic groups linked to the snail trade. We interviewed 672 people (1 person per household), conducted 6 focus groups, and interviewed 80 key actors belonging to 5 subcategories. The snail was the most widely consumed bushmeat and an important source of income, particularly for women and unemployed youth. Insecure and scarce livelihood alternatives, mostly in rural areas, were reported as drivers for trade involvement. Snail harvesting was more frequent in poorer households with low occupational diversity. Selling tended to occur in households that were well-established in the community and had a higher proportion of children. Both were stimulated by the proximity of communities to the native forest. Buying snails was common in all demographic groups, but it was linked to wealth and occupational diversity. Interventions to manage the impact of this introduced species on the valuable ecosystems of the island should involve multiple sectors of society to ensure societal support. This requires robust consideration of the welfare of vulnerable demographic groups that benefit from the species.

Nematodes of concern to public and animal health associated with the invasive snail Achatina fulica, in Sergipe, Northeastern Brazil

The giant African land snail Achatina fulica is known to be the intermediate host of a number of nematode species that are prejudicial to human and veterinary health, being also an agricultural and urban pest. The present study investigated the presence of nematodes in A. fulica and other terrestrial mollusks in 24 municipalities of Sergipe State, northeastern of Brazil, in the dry and rainy seasons. In 2019 and 2020, the specimens were collected in standard 20 m × 10 m plots (10 min/01 collector), while in 2021, they were collected by convenience sampling. The nematode species were identified based on sequencing of the mitochondrial Cytochrome C Oxidase Subunit I (COI) gene and the ribosomal nuclear Internal Transcribed Spacer (ITS 2). Specimens of A. fulica infected with Angiostrongylus cantonensis, a nematode that causes eosinophilic meningitis (EM) in humans and animals, were collected in four municipalities. Two nematodes of veterinary importance were also identified, Aelurostrongylus abstrusus and Cruzia tentaculata in seven municipalities. This is the first record of Cruzia tentaculata in Sergipe. Free-living nematodes were also found in 18 municipalities. One of these species – Caenorhabditis briggsae – was identified in the municipality of Itabaiana. Specimens of other mollusks species were also collected. Only one of these mollusks, C. fasciata from Japaratuba, was found infected with free-living nematodes. A. fulica showed greater positivity for nematodes in the dry season, especially in the regions of Lower São Francisco River, Greater Aracaju and South Central Sergipe. The probability of infection increased when mollusks were larger and more recurrent in plots. Given that A. cantonensis is the etiological agent of EM and was found associated to A. fulica in four municipalities, it will be important to implement programs of continuous monitoring of the mollusk's fauna, combined with educational programs that provide information necessary to control A. fulica.

Comparative reproduction performance of Giant African Land Snail (Archachatina marginata) fed with the leguminous plant Leucaena leucocephala

The study was carried out between July and October 2022 at the sub–station of the Faculty of Agriculture Research and Teaching farm to assess the reproductive performance of Archachatina marginata fed the leguminous Leucaena leucocephala leaf meal as feed additive. 208 adult snails were randomly partitioned into 4 treatments and 4 repetitions of 13 comparable snails (weight and size). The treatment T0 (control) received only the experimental diet as described while three other treatments received not only diet but, L. leucocephala leaf meal at 0.25%, 0.5% and 0.75% for a period of 12 weeks. In each treatment, every morning, the substrate of each breeding bucket was stirred entirely and minutely to collect the eggs to determine the laying and morphometric characteristics of the eggs. The eggs were then placed 10 cm deep in loose soil substrates until hatching to evaluate the characteristics of the fecundity. The unhatched eggs were opened, and the state of embryonic development observed to determine early embryonic mortality rate and late embryonic mortality. At the end of the experiment, animals of each replicate were sacrificed; the hemolymph was collected determine the total cholesterol and protein. The results showed that the characteristics of reproduction were affected with graded level of L. leucocephala. The highest number of eggs laid (17.29 ± 13.44) and the number of clutches (268.91) was recorded in animals receiving 0.5% and 0.75% L. leucocephala in the diet respectively while the highest value of fecundation rate (95.50 ± 8.80), hatch rate (94.55 ± 9.36), and hatchability (98.99 ± 3.15) was registered in the treatment that received 0.75%. The highest value of total protein and cholesterol was recorded in the same treatment. In conclusion 0.75% of L. leucocephala can be added in the diet of adult snail to increase its reproductive performance.

GROWTH PERFORMANCE AND LIPID PROFILE OF ARCHACHATINA MARGINATA (GIANT AFRICAN LAND SNAIL) FED VARYING LEVELS OF RIPE EGGPLANT FRUITS BASED DIETS

The performance of African giant land snails (Archachatina marginata) fed ripe eggplant fruits was studied using eighty-four (84) juvenile (four months old) Archachatina marginata for eight (8) weeks. The study evaluated the snails' growth performance and lipid profile (total cholesterol, low-density lipoprotein, high-density lipoprotein and triglycerides). The snails were divided into four treatment groups, with twenty-one (21) snails per group in a completely randomized design (CRD). Treatments 1, 2, 3 and 4 had varying levels of ripe eggplant fruits at 0%, 5%, 10% and 15% inclusion levels respectively. Isocaloric and isonitrogenous feeds and water were provided ad libitum, while other management practices were strictly adhered to. The results showed no significant differences (P&gt;0.05) in growth performance across treatments. The results also revealed that total cholesterol decreased (P&lt;0.05) significantly as the levels of ripe eggplant fruits increased across treatments. There were no significant differences (P&gt;0.05) in low-density lipoprotein and triglycerides, while high-density lipoprotein differed (P&lt;0.05) significantly across treatments. The result also showed a linear increase in high-density lipoprotein ("good" cholesterol) as the levels of ripe eggplant fruits increased across treatments. Therefore, a 15% inclusion level of ripe eggplant fruits in the diet of Archachatina marginata reduces total cholesterol levels and increases high-density lipoprotein without any adverse effect on growth. The study recommends using ripe eggplant fruits to formulate diets for animals with high cholesterol content and high levels of low-density lipoprotein in their meat.

Enhancing Giant African Land Snail (Archachatina marginata) production with Thymus vulgaris (Lamiaceae) in the south-west region of Cameroon

The study was designed to determine the effect of Thymus vulgaris leaf meal on the production of Archachatina marginata. Two hundred and twenty-four adults’ snails were divided into four treatments of 14 snails and four replicates. Treatment T0 received only the experimental diet while three other treatments received diet with different inclusion level of T. vulgaris leaf meal at 0.25%, 0.50%, and 0.75%. Feed and leave were quantified using an electronic weighing scale daily. The results obtained show that, feed intake was significantly higher (P &lt; 0.05) in animals receiving 0.75% T. vulgaris compared to other treatments. Likewise, the values of heart, pedal mass were higher in animals receiving 0.25% inclusions of T. vulgaris in the diet. Low relative weight variations in the internal organs across treatments were observed but significant differences occurred regarding only the shell weight and ovotestis. The proximate analysis of snail flesh results obtains shows that dry matter was significantly (P &lt; 0.05) highest in animals receiving 0.25% T. vulgaris in the diet. Minerals analyzed were also significantly (P &lt; 0.05) affected by the inclusion of T. vulgaris in the diet. In conclusion, incorporation of T. vulgaris leaf powder at 0.25% can be recommended in the diet of snails.

Parasitic Fauna of Achatina Achatina in Otuoke Community, Ogbia Local Government Area, Bayelsa State

The Giant African land snail, Achatina achatina, is an invasive species recognized for being a serious agricultural pest and vector for diverse parasites that cause diseases in humans. This study assessed the prevalence of parasites harboured by the snails collected from bushes in the Otuoke community of Bayelsa State, Nigeria. The snail samples were collected and transported to the laboratory for examination using wet mouth preparation and teasing methods. Subsequently, they were classified by size into small, medium and large. The body organs were individually teased and examined under the microscope. 122 snail samples (32 small, 54 medium, 36 large) were randomly collected for this study and examined for the presence of eggs or larvae of parasites, out of which 108 (88.5%) were infected. The larvae of only two species of parasites, Angiostrongylus cantonensis (90.1%) and Strongyloides stercoralis (9.9%)) were recovered from the infected snails, with A. cantonensis being most prevalent, 737 (90.1%). The parasites were most prevalent in the medium snails (42.6%), followed by the small size (23.8%) and then, the large size snails with the least prevalence of infection. The slime, intestine and stomach were infected, with the parasites being more in the slime (88.5%) than any other body parts. Since the Giant African land snail serves as an intermediate host for several parasites, a thorough understanding of the snail parasites' lifecycles and modes of transmission to humans is important, for human health and welfare, sustainable snail farming, and for maintenance of snail biodiversity.

Comparative diagnostic imaging in giant African land snails (Achatinidae).

Giant African land snails (GALS) have become increasingly popular, for example, as pets or in kindergartens in Europe, but little is known about their clinically relevant anatomy, diseases, or further details in diagnostic imaging. The present study focuses on the techniques and image interpretation of radiography, computed tomography, and sonography in GALS. The aim of the study is to find the most appropriate imaging tool to visualize the various organs within the mantle cavity (also known as visceral mass) in GALS. The detailed anatomy of GALS is presented with numerous figures of the different imaging techniques. The sensory organs and nervous system will not be part of the present study.

Investigating the potential of African land snail shells (Gastropoda: Achatininae) for amino acid geochronology

Aragonitic calcium carbonate (CaCO3) terrestrial mollusc shells with complex shell microstructures, such as those in the African subfamily Achatininae, have the potential to be used to build amino acid geochronologies across the African continent. However, as different microstructural shell layers are likely to have different protein compositions, sampling strategies need to be developed to identify the most appropriate shell portion to target. To test possible variability in protein degradation rates between microstructural layers, sampling of a single microstructural shell layer (the ‘nacreous’ layer) was compared to sampling all three aragonitic layers ('3AL') in modern and fossil shells. Reliable isolation of the nacreous layer in all samples proved impractical, and additional complications arose due to mineral diagenesis induced by sampling with a drill. Pleistocene fossils of Lissachatina sp. and modern specimens of Achatina tavaresiana Morelet, 1866 were shown to have an intra-crystalline protein fraction. The 3AL shell portion adhered more closely to closed-system behaviour in heated modern, and fossil, samples. The intra-crystalline protein degradation (IcPD) patterns of Achatininae fossil samples were not consistent with IcPD under forced degradation experiments at high temperatures in the laboratory. However, reliable degradation trends were observed in the 3AL shell portion, demonstrating the potential of fossil achatinids for building relative amino acid geochronologies across Africa.

Process optimization for blended waste frying oil in biodiesel production using CaO derived from African periwinkle shell catalyst through response surface methodology

Biodiesel is one of the renewable energy alternatives for fossil fuel because of its biodegradability, no toxicity, and environmentally friendly nature. Investigations have been made on transesterifying blended waste frying oil (BWFO) into biodiesel using African periwinkle shells (APS) heterogeneous catalyst. The BWFO, a mixture of 60:40 groundnut oil and waste palm oil, usually causes serious environmental problems when indiscriminately disposed. After being calcined, the non-activated APS (RAPS) was further sulphonated to create an acid-activated APS (AAPSA) catalyst. Scanning electron microscopy (SEM), X-ray fluorescence (XRF), the Brunauer-Emmett-Teller method (BET), and other techniques were used to characterize the produced RAPS and AAPSA. Gas chromatography-mass spectrometry (GC-MS) and Fourier-Transform Infrared Spectroscopy (FTIR) were used to evaluate the produced biodiesel. Besides, a series of physiochemical properties including acid value, density, kinetic viscosity, flash point, cloud point, pour point, and other fuel properties of produced BWFO, were evaluated using ASTM standard methods. The central composite design (CCD) of the response surface methodology (RSM) was utilized for modeling and process optimization of biodiesel production from BWFO.The characterization results revealed that CaO (62.07 %) is the main constituent of AAPSA. The RPSA's pore volume and BET surface area were 0.34 cm3/g and 68.93 m2/g, respectively. BET surface area (30.9%) and pore volume (48.2 %) increased for the AAPSA. The significant increase in surface area and pore volume of AAPSA indicates an enhanced number of acid sites and catalytic activity of the acid-modified catalyst towards higher produced biodiesel yield. The optimal conditions for the reaction temperature, reaction time, catalyst loading, and methanol to oil ratio (mtOH/oil) were 55 °C, 142.5 min, 2.5 wt%, and 14.25:1. This resulted in the maximum yield of biodiesel, which was 91.5 %. Moreover, the AAPSA catalyst performed excellently, and the resulting biodiesel fuel's properties are comparable with those of ASTM D6751 and EN 14214 standards. Hence, AAPSA is a potential solid acid bifunctional heterogeneous catalyst to produce biodiesel from BWFO. Therefore, this study's novelty comprises the synthesis of solid acid bifunctional heterogeneous catalyst from giant African land snail shells and the optimization of the process variables involved in the production of biodiesel from BWFO.

Anti-feedant and Molluscicidal Activities of Selected Spices Against Achatina fulica (Gastropoda: Achatinidae)

The application of biopesticides is progressively encouraged for its advantages associated with environmental safety and high biodegradability. The objectives of this study were to compare the phytochemical constituents, anti-feedant, and molluscicidal activities of spices against the giant African land snail, Achatina fulica. The spices evaluated were clove (Syzygium aromaticum), cinnamon (Cinnamomum verum), black pepper (Piper nigrum), cumin (Cuminum cyminum) and coriander (Coriandrum sativum). Phytochemical constituents of spices were screened by qualitative standard protocols. Anti-feedant activity was investigated by the leaf disc no-choice bioassay method and molluscicidal activity was evaluated by a 72-h contact toxicity test. The phytochemical screening showed positive results for tannins, saponins, alkaloids, flavonoids, terpenoids, and phenols in clove, cinnamon, cumin and coriander ethanolic extracts whereas only tannins, alkaloids and terpenoids were found in the black pepper ethanolic extract. The leaf disc no-choice bioassay revealed that all spices demonstrated anti-feedant activity (p&lt;0.05, compared to control). However, only clove (85.33±3.09%), cinnamon (72.35±3.41%) and coriander (81.54±3.88%) ethanolic extracts showed high feeding inhibition activity, whereas black pepper (68.85±3.22%) and cumin (68.96±3.12%) had moderate anti-feedant activity. In the contact toxicity test, clove ethanolic extract (52.67±1.53%) showed moderate molluscicidal activity, meanwhile cinnamon (19.34±2.08%), black pepper (16.65±1.15%), cumin (18.96±1.42%) and coriander (22.67±1.37%) demonstrated low molluscicidal activity. In conclusion, all spices tested in this study showed the presence of important secondary metabolites that contribute to anti-feedant and molluscicidal activities at differening levels.

Children's Relationships with a Non-Vertebrate Animal: The Case of a Giant African Land Snail (Achatina fulica) at School.

Employing living animals in educational settings is popular and may assist learning. Human-animal relationships are considered fundamental for the effects of animal-assisted interventions (AAI) on successful learning. Key studies on AAI emphasize dogs, or other large-brained vertebrates, while AAI with non-vertebrate species is a yet rather unexplored field. However, bringing non-vertebrate species to school has ethical and practical advantages. In an exploratory study, we tested whether seven-years-old children would form caregiving relationships with a Giant African land snail (Achatina fulica). Prior to the survey, the snail had been kept inside a terrarium in the classroom for seven months. We employed a questionnaire for measuring children's pet attachment to assess the children's relationships with the snail. The observed relationship scores with the snail were intermediate to high and did not differ from same-aged children's attachment scores with their dogs, cats, and rabbits. No differences due to gender were observed. Children potentially developed caregiving attitudes and empathy towards the snail, and thus, the presented results indicate potential benefits from employing a non-vertebrate species in educational settings, as well as for animal-assisted therapy. The specific features of A. fulica are discussed in the frame of human-animal interactions, learning, and anthropomorphism.

Effects and Cost-Benefit of Low and High Protein Levels in Snail Diets with Constant Levels of Energy and Calcium

Snails are invertebrates with soft segmented shells. Snail farming is still at the infant stage compared to other farming enterprises because of limited information on the nutrient requirement of the animal. Therefore, a 12-week study was conducted to determine the effect of snails’ diets containing low and high Crude protein (CP) levels with constant level of energy and calcium on the growth performance of African giant land snail Archachatina marginata. In a completely randomized design, a total of 120 snails of the same weight and breed were randomly allotted to five (5) different dietary treatments: PR1 (20% CP), PR2 (22% CP), PR3 (24% CP), PR4 (26% CP) and PR5 (28% CP) with constant energy (2.6 Mcal/kg Metabolizable Energy) and calcium level. The snails were placed in 12 experimental compartments each measuring 0.5x 0.5m2. Results revealed that the body weight gain, feed intake, cost of feed per kg weight gain and dressing percentage yield was significantly (p &lt; 0.05) higher at the 28% CP. Furthermore, results showed significant (P&lt; 0.05) interactions between protein across the treatments performance indices, shell length, shell width, feed cost per kg weight gain and dressing percentage yield. Feed intake decreased significantly (p &lt; 0.05) at 20% CP level while the FCR values decreased (p &lt; 0.05) at 28% CP level. Shell length, width and thickness was enhanced (p &lt; 0.05) at 20% CP level. Also, the Feed cost per kg weight gain was observed to be significantly (p &lt; 0.05) reduced at the 24% CP. The results obtained in the present study showed that the dietary protein of 24% CP, with constant energy of 2.6Mcal/kg ME is optimally suitable for the growth of African giant land snails Archachatina marginata at reduced cost.

Evaluating different diets on the growth performance of mud crab (Scylla serrata)

The purpose of this study was to assess the potential of natural feeds for the sustainable grow-out aquaculture of mud crabs as an alternative to commercially available mud crab feeds. This study employed a completely randomized design that includes five feed treatments including trash fish, African land snail, horn snail, edible frog, and mud snail. There were three replicates for each treatment with three cages each located in a concrete tank with an area of 12m2. Each cage contained one lean crab. The crabs were fed twice a day, at 7 a.m. and 8 p.m. with an amount adjusted to 7% of the crab's body weight. After the first 21 days, all the crabs were harvested by draining out the tank water and the pincers of the crab were tied with a string to enable handling. The results showed that the highest growth performance in weight gain and condition factor was seen in African land snail feed with a feed conversion ratio of 1.38, indicating a high-quality feed. It also showed an impressive ROI of 96.8% which can be confirmed that this kind of feed might be a viable mud crab feed for both commercial scale and industry.

Use of plant extracts to control activities of the invasive giant African land snail Achatina fulica

Giant African land snails (Achatina fulica; GALS) are a highly invasive herbivore and pose serious threats to native species and that could disrupt ecosystems. Various botanical extracts have been used as molluscicides to control mollusks for pest management. We aimed to identify the effects of neem (Azadirachta indica) and titepati (Artemisia vulgaris) to reduce GALS activities and survival using solutions of fresh neem leaf and titepati leaf, bark, and root. We found a fast movement in the GALS only in the extraction groups while the lethargic movement was lower in mulching method. A significant association of control groups with different extraction groups along with mulching treatment (p&lt;0.05) however, no differences were observed among different extractions at 2.5% and 5% concentrations. Among the treatments, Neem leaf at 5% concentration was found to be effective as it helped immobilize the samples after ten days whilst other treatments required minimum 14 days to be effective. We recommend further studies of titepati and neem as control agents to reduce crop and vegetable damage from GALS.

Evidence for large land snail cooking and consumption at Border Cave c. 170–70 ka ago. Implications for the evolution of human diet and social behaviour

Fragments of land snail (Achatinidae) shell were found at Border Cave in varying proportions in all archaeological members, with the exception of the oldest members 5 WA and 6 BS (>227,000 years ago). They were recovered in relatively high frequencies in Members 4 WA, 4 BS, 1 RGBS and 3 WA. The shell fragments present a range of colours from lustrous beige to brown and matt grey. The colour variability can occur when shell is heated. This possibility was explored here through experimental heating of giant land snail shell fragments (Achatinidae, Metachatina kraussi - brown lipped agate snail) in a muffle furnace from 200 to 550 °C for different lengths of time. Colour change, weight loss, and shattering of the heated samples were recorded. Transformation of aragonite into calcite and the occurrence of organic material was investigated by means of Infrared and Raman spectroscopy. Scanning electron microscopy was also used on selected specimens to help identify heat-induced transformation as opposed to taphonomic alteration. The identification on archaeological fragments of features produced by experimentally heating shells at high temperatures or for long periods has led us, after discarding alternative hypotheses, to conclude that large African land snails were systematically brought to the site by humans, roasted and consumed, starting from 170,000 years ago and, more intensively between 160,000 and 70,000 years ago. Border Cave is at present the earliest known site at which this subsistence strategy is recorded. Previous research has shown that charred whole rhizomes and fragments of edible Hypoxis angustifolia were also brought to Border Cave to be roasted and shared at the site. Thus, evidence from both the rhizomes and snails in Border Cave supports an interpretation of members of the group provisioning others at a home base, which gives us a glimpse into the complex social life of early Homo sapiens.

An A to Z of enhancements: G is for growing

A focus on plants has given children experiences of growing butterflies and African land snails. By Amy Jackson

Modeling and optimization of transesterification of rubber seed oil using sulfonated CaO derived from giant African land snail (Achatina fulica) catalyst by response surface methodology

Rubber seed oil (RSO) is an abundance of low-cost non-edible vegetable oil and an attractive resource for biodiesel production through transesterification. The study aims to model and optimize the transesterification of RSO to biodiesel using sulfonated CaO derived from snail shells as a bifunctional heterogeneous catalyst. We prepared the raw snail shell (RSS) catalyst by calcination and sulfonated it to produce an acid-activated snail shell (AASS) catalyst. We used the central composite design (CCD) of the response surface methodology (RSM) to model and optimize the transesterification process. The X-ray fluorescence (XRF), Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), and Brunauer-Emmett-Teller method (BET) were used to characterize RSS and AASS catalysts.The results show that CaO (95.6%) is the major component of RSS. The maximum biodiesel yield of 97.6% was obtained at a 12:1 methanol to oil molar ratio, 80 °C reaction temperature, 2.5 h reaction time, and 2.5 wt% catalyst loading with a quadratic regression model. The recyclability of the catalyst shows six runs without an appreciable decrease in biodiesel yield. The AASS catalyst can perform excellently as a bifunctional solid acid heterogeneous catalyst, and the fuel properties of the biodiesel produced compare favorably with American society for testing and materials (ASTM D6751) and European standard methods (EN 14214) standards.