Vampire Bats on a Treadmill, Medicinal Leeches at London Zoo, and Nutrient Foraging in Spiders: Naked Scientists Animal News

Overview

The Naked Scientists present an animal themed news special featuring vampire bats on a treadmill to study metabolism, medicinal leeches returning to UK waterways with breeding at London Zoo, and nutrient specific foraging in spiders, plus an Asian elephant using a hose as a tool. A listener question on ship propellers rounds out the episode.

• Vampire bats powered by amino acids as they run on a treadmill, revealed by carbon-13 tracing.
• Conservation and breeding efforts bring medicinal leeches back to UK ponds with insights into their saliva chemistry.
• Spiders show nutrient driven foraging decisions that differ by species, life stage and sex, with potential agricultural applications.
• Elephants demonstrate tool use with a water hose controlled by the trunk, suggesting cognitive and social factors in learning.

Introduction

The Naked Scientists host an animal themed news special, diving into recent biology and behavior research across different species. The episode features vampire bats and their metabolism, medicinal leeches and their return to UK waterways, nutrient based foraging in spiders, and an intriguing case of elephant tool use. A listener question about propeller placement adds a physics angle to the mix.

Vampire Bats on a Treadmill

Ken Welch from the University of Toronto explains a novel study that uses a treadmill instead of wind tunnels to examine vampire bat metabolism during sustained running. The goal is to understand how these bats manage a high energy budget on a diet rich in protein from blood. The researchers fed the bats a blood meal enriched with a carbon-13 labeled amino acid before running, allowing them to trace which compounds are oxidized to produce energy. By analyzing exhaled breath and CO2, they found a heavy carbon signature indicating rapid amino acid oxidation, suggesting these bats rely heavily on amino acids as fuel during intense activity. The team hypothesizes that pathways for carbohydrate and lipid metabolism are downregulated while amino acid catabolism is upregulated, a metabolic adaptation that may differ from other blood feeders.

Medicinal Leeches and London Zoo

The episode then shifts to conservation, with medicinal leeches returning to UK freshwater systems. Naomi Ewald of Freshwater Habitats Trust discusses their ecological role and the need to restore high quality ponds that can support wild populations. Leeches are large, blood-feeding organisms with distinctive patterned bodies, and their saliva contains anticoagulants and other compounds that have medical relevance for healing and tissue repair. London Zoo is involved in breeding programs under controlled temperature regimes to promote breeding and dormancy cycles. The researchers emphasize the value of leeches as ecological indicators for pond health and as part of habitat networks across landscapes.

Spiders and Nutrient Specific Foraging

Jordan Cuff from Newcastle University presents work on nutrient specific foraging in spiders. The study shows that different spider taxa display preferences for prey that differ in carbohydrate, lipid, and protein content. Money spiders on sheet webs tend to consume carbohydrate rich prey, while wolf spiders that hunt actively prefer lipid and protein rich prey. Adults and males lean toward carbohydrate rich prey, whereas juveniles and some females invest more in protein and lipids for growth and reproduction, respectively. The discussion also covers how spiders might detect prey nutrients, likely through senses other than strong smell and possibly through learning from vibrational cues. The potential application includes manipulating predator foraging to reduce crop pests by targeting lipid and carbohydrate rich prey.

Elephant Tool Use

Lina Kaufmann reports on Mary the Asian elephant in Berlin Zoo who uses a water hose as a tool to shower. This represents long term empirical evidence of elephant tool use, with trunk dexterity allowing Mary to manipulate the hose for body care and comfort. The interview explores whether learning occurred socially by observing humans or other elephants, and whether other elephants intervene in Mary’s experiments. The researchers stress the need for more long term studies of elephant cognition and tool use to understand how elephants comprehend tools and human-made devices.

Question of the Week and Closing Thoughts

The episode closes with a physics question from a listener about why ship propellers are mounted at the back of boats while aircraft propellers are at the front of fuselages. Cambridge physicist Andy Wheeler explains the roles of mass density differences between air and water, flow entering the propeller, engine weight distribution, and practical considerations for loading and stability. The show signs off with an invitation to a future program on nuclear power for space exploration.