Biomedical Engineering Senior Design – Section 2

Preliminary Report

Team Members: Vamsi Varra, Aditya Yadavalli, Michael Mathison

Project Scope:

The health of any animal in zoo captivity depends on the ability of the caretakers to

emulate its natural environment. Oscar the otter is one such animal, and currently its exhibit in

the Saint Louis Zoo lacks many characteristics typical of an otter’s habitat in the wild. North

American river otters thrive in enclosures that are two-thirds land and one-third water, but the

Saint Louis Zoo’s enclosure has the opposite ratio. Additionally, the space does not give much

opportunity for hunting and foraging activities essential for the otter’s fitness. Our goal is to

invent a device that provides enrichment for the otter while tackling some of the other afore-

mentioned issues.

There are many constrictions on possible solutions that the zoo has not been able to

work around. First, the otter tends to push items into the pool, which cannot be retrieved until

the pool is completely drained, which occurs only once every four months. Second, any toy

given to the otter has to be small enough so that the otter cannot use it to climb out of the

enclosure. Finally, otters are incredibly strong, so the solution has to be sturdy enough that the

otter does not destroy it. We currently are not sure what our source of funding for the project will

be and will shortly approach either faculty or the zoo for potential resources.

Although the class only requires either a prototype or a physical representation, we plan

to see a functional product to completion, so the zoo will have something tangible that they can

immediately put to use. In order to do this, we are enlisting the help of an undergraduate

electrical engineer, Kunal Patel, whose expertise in circuitry will be very valuable. We hope that

our solution will also be easily replicable so that it can be put to use in otter exhibits in other

zoos.

1

Background:

The North American river otter, species Lontra Canadensis is listed in Apendix II of the

Convention on International Trade in Endangered Species of Flora and Fauna. Appendix II

contains a list of species that are not currently at risk of being endangered, but may become so

without tight regulations. They have been virtually eliminated in many parts of their natural

range, especially in highly populated regions in the midwest and eastern united states.

However, recent conservation efforts have been able to restore their numbers significantly.

The species is active all year round and is most active from dusk till dawn. Its aquatic movement

is performed by “quadrupedal paddling, forelimb paddling, alternate hind-limb paddling,

simultaneous hind-limb paddling, or body and tail dorsoventral undulation.” The tail is used for

stability and quick burst of movement. While swimming near the surface the otter must remain in

motion, and tends to keep its eyes, ears, and nostrils above water. On land, they can “walk, run,

bound, or slide.”

Being carnivorous, the North American river otter’s diet composes mainly of fish and

crustaceans. They also occasionally consume frogs and waterfowl, and rarely eat other

mammals. They forage in a variety of habitats, including rivers, lakes, streams, and marshes.

Their general foraging behavior involves submerging in water and using eyesight in clear water

or their highly sensitive whiskers in murky water to locate prey. They can use either their mouths

or their retractable claws to quickly snatch prey. Otters are known to use tools, such as rocks, in

order to free the meat of shellfish from their shells by holding the tool in its paw and repeatedly

beating the shell of its prey. Otters learn these behaviors mostly through observational learning.

For example, it has been observed that mother otters will capture fish and then drop the fish

back into water so that the otter offspring can recapture the fish in the same manner.

2

Specific Design Requirements:

The main goal of our solution is to provide environmental enrichment for the otters,

which improves their overall health and contributes to their lifespan. It is recommended that any

enrichment program that is implemented include the following: “goal-setting, planning and

approval process, implementation, documentation/record-keeping, evaluation, and subsequent

program refinement.” We will be required to have back-and-forth discussions with the

zookeepers to in order to follow each of the above steps. The steps serve to ensure that the

solution is safe and can also be provided on a variable schedule in order to prevent habituation.

The AAZK Enrichment Committee provides a cautionary list of key questions that should be

answered for any enrichment program:

Can the animal become caught in it or trapped in it?

Can it be used as a weapon?

Can an animal be cut or otherwise injured by it?

Can it fall on an animal?

Can the animal ingest it or any part of it?

Is any part of it toxic, including paint or epoxy?

Can it be choked on or cause asphyxiation/strangulation?

Can it become lodged in the digestive system and cause impaction or linear obstruction?

Can it destroy an exhibit?

If food enrichment is used, will it increase the chance of the animal’s obesity?

Do animals show signs of allergies to new items?

Does the enrichment cause abnormally high stress levels?

Does the enrichment cause high level activity for extended periods of time that would be

abnormal?

3

Shannon Santangelo, one of the otter’s caretakers mentioned another question, specific

to this particular exhibit: Can the object be used by the animal to escape the exhibit?

There has been extensive research performed regarding other aspects of the captivity of the

North American river otter, much of which has been compiled into the Otter Care Manual

created by the AZA Small Carnivore Taxon Advisory Group. Since otters are naturally semi-

aquatic creatures, the exhibit has an aquatic portion that is monitored using coliform bacteria.

However, this does not account for non-biotic toxicity that may be introduced into the water.

Loud noises may be frightening to the otters, and they should not be subjected to long-term,

high-pitched sounds. Careful considerations are supposed to be given to the exhibit design. The

optimal land-to-water ratio for otters is 3:1 to 4:1. However, the St. Louis Zoo’s otter exhibit has

a far from ideal ratio of 1:2 land to water. In addition, it is beneficial for the otter to be provided

with climbing structures that the exhibit currently lacks.

Figure 1 – Oscar’s Exhibit

4

Exploration of Current Solutions:

The St. Louis Zoo itself has a few rudimentary solutions already that we can look

towards for ideas. Currently, one of their main enrichment attempts is a simply bucket. It is

about two feet tall and has a diameter of about 1 foot. They have seen that Oscar loves

interacting with the bucket, throwing it around and diving in and out of it, when it’s in the water.

They also use a variety of plastic balls and boxes that can be thrown around and interacted

with, but unfortunately, quite a few of these get destroyed by the otter fairly easily.

All of the toys the zookeepers showed us were made of a similar material. They were all some

sort of plastic polymer but of various different colors. None of the objects seemed too complex

in structure and they all lacked any kind of sharp corners or protrusions that could break off.

Other than these toys, the zoo does not seem to have tried any novel solutions to the lack of

enrichment currently facing the otter.

However, other zoos have taken a crack at implanting new, innovative ideas in hopes of

stimulating their otter populations. One such example is the Smithsonian National Zoo. Last

spring, they attempted to provide enrichment for a group of Asian small-clawed otters through

music. They placed a keyboard outside of the otters’ cage so they could either reach through

and press keys on the keyboard, or sit back and observe the other otters doing so. A video on

the Smithsonian National Zoo’s website shows them actively engaging with the keyboard.

5

Figure 2 – Otters Playing Piano at Smithsonian National Zoo

Another study did not disclose the location of the zoo at which it occurred, but it detailed

an otter enrichment program involving a public interactive feeding exhibit, in which several

different types of food were used, one of which was live crickets. The manner in which the

interactive exhibit worked made the hunting of the live crickets more engaging than all the other

options. The otters, also Asian small-clawed otters, had the most motivation to capture the live

crickets when presented the opportunity.

A researcher at the Seneca Park Zoo in Rochester, New York presented a few food

based enrichment items to their North American river otters. The options presented were live

fish, frozen fish, swim tubes, a swim tube, and PVC pipe scent tubes. The researcher found that

the food options, especially the live fish, most significantly deterred a repetitive swimming patter

that otters tend to perform when under stimulated.

Several other zoos have also tried enrichment-type programs. North Carolina Aquariums

employs tree stumps, pine straw, and branches to keep their otters enriched. The Phillips Park

zoo tried olfactory enrichment, scenting plastic balls with different food odors, including cod oil,

ground chuck juices, and fish juices, showing that otters were preferentially attracted to some of

6

the toys over others. At the Minnesota Zoo, a six-sided bamboo hoop was prepared with holes

drilled into it in which food could be placed.

Patent/Literature Search:

To maintain a healthy and normal lifestyle, animals in captivity require a great deal of

artificial stimulates and objects to interact with that best mimic a natural environment. A variety

of studies have been published on the topic of the best possible enrichment ideas for otters in

captivity. The Association of Zoos and Aquariums (AZA) compiled a Northern American River

Otter Care Manual that denotes all of the approved existing solutions to otter enrichment.

The solution that is to be designed in this project is to provide the maximum amount of

environmental enrichment possible for the River Otter at the St. Louis Zoo. There is a great deal

of literature and studies that investigate pertinent physical traits of otters and behavioral trends.

Listed in Table 1 are the various studies with associated synopses. Existing solutions, as

mentioned earlier and in the Otter Care Manual, are a combination of a variety of routine

objects, which are not patentable. For example, a great deal of the environmental enrichment in

the habitat itself is foliage, and appropriately placed ledges, and water flows. Additionally, a lot

of the social enrichment comes in the form of PVC pipes, barrels of water, and burlap blankets

and hammocks. The Boomer Ball, an indestructible, large, animal enrichment polyethylene ball

is the most common man-made existing solution to promote a healthy, active, and entertaining

lifestyle to the river otters. This is not a patentable device. However, there are a few patented

basic toys that are used for otter enrichment, listed in Table 2. Furthermore, it is important to

note that many of the existing solutions must be monitored carefully due to a tendency to

become dangerously adherent if soaked in water for too long.

7

Table 1

Study Name Author SummaryLontra candensis Lariviere et al. This study provides a great deal of

background on the general anatomy and structure of the Lontra candensis in addition to its ecology and its reproductive behavior

Foraging Behavior and Feeding Ecology of the Otter Lutra Lutra: A Selective Review

David N. Carss This study highlights the foraging behavior, habitat psychology and dietary needs of the river otter.

AZA Otter Care Manual AZA Small Carnivore Taxon Advisory Group

This manual summarizes every aspect from typical environment, behavior management, animal health care, and future research.

Bite Forces and Evolutionary Adaptations to Feeding Ecology in Carnivores

Christiansen et al.

This study summarizes the bite strength and histology of jaw development in Carnivores closely related to the otter.

Table 2

Patent Name Publication Number

Description of Product/ Relevance to Otter Enrichment

Animal Enrichment Devices

US20140069338 This is a mobile device form which the animal can attempt to withdraw food from. The animal’s effort to obtain food will be rewarded by this device. Used to reward otters.

Combined Kennel Door and Latch

USD367734 This is a kennel where the animal is housed and transported in. A latch that cannot be mistakenly opened by the animal is located on the outside of the kennel. Patent was referenced by the creators of Vari-Kennel, the kennel used for otters.

Monofilament Ribbon Pile Product

US3332828 This is the patent for what is more commonly known as Astro-Turf. This is used to imitate grass an otter would encounter in a real habitat.

Dog Chew Toy USD348959 This product is a long rope with rubber fiber hybrids interspaced throughout the toy allowing for graspable locations. This product is used to promote activity and enrich the social aspect of the river otter in captivity.

Bobbin US2170773 An old patent for the spool holding thread or wire during machine sewing and lacemaking. This is replicated on a larger level for otters as toys for further activity and enrichment.

Super-Enhanced, Adjustably Buoyant Floating Island

US20110146559 This is a floating island used to decorate ponds and other bodies of water. This is used as further enrichment to emulate a natural habitat

8

for the otter.

Preliminary Mathematical Analysis:

It is imperative that various mathematical calculations and facts about the size and

strength of the North American River Otter are stated before proceeding with a design. These

calculations and facts are listed below.

Otter Weight: 11 to 30 lbs

Body Size: 55 to 80 cm

Tail Size: 30 to 50 cm

Solid food consumption starts at 9-10 weeks of age

Can swim up to 20 meters underwater and at 11 km/h.

Highly sensitive to any kind of pollution in water: threshold value for toxicity of mercury

poisoning is 20-30 ppm

Fur Thickness: 12 to 17 mm.

Estimated Bite Strength 223.4 Newtons

Can climb and jump heights up to 6 feet

Consumes between 15%-20% of total body weight daily.

To prevent escape, wire netting must have a mesh netting of less than 2 inches.

In groups of two or more otters spend 43.6% of the time investigating, 30.7% wrestling,

7.4% traveling, 5.92% marking, 5.5% playing, 2.76% grooming, 2.3% sliding, and 1.5%

rolling and rubbing.

Large habitats- can range anywhere from 2- 28km from home river source. Requires at

least a 3:1 or 4:1 water to land ratio.

Current dimensions of habitat (statistics acquired from Shannon Santangelo our contact

at the St. Louis Zoo)

9

o Holding: 8' x 4' chain link enclosure (2" x 2" openings). Not connected to the

habitat. Animal moves up a 25 foot keeper hallway to access this holding space.

o Mulch area: ~4ft x 5ft

o Sand area: ~13ft x 4ft

o River rock: ~4ft x 5 ft

o Concrete areas: Shorelines are 2-4ft wide; steps: ~1.5ft x 9ft

Preliminary Design Schedule:

9/18

Finish rough draft of preliminary report and send to Dr. Klaesner for review

9/19

Turn in finished version of preliminary report

9/22

Preliminary oral report given by Vamsi

9/27 – 10/04

Brainstorm of all possible solutions

10/22

Finish rough draft of progress report and send to Dr. Klaesner for review

10/24

Turn in finished version of progress report

10/27

Progress oral report given by Aditya

11/03 – 11/06

Narrowing down of solutions to one that we will implement

11/10 – 11/27

10

Detailing of final solution and making of prototype

11/19

Finish and turn in peer reviews

11/29

Finish rough draft of final report and send to Dr. Klaesner for review

12/1

Turn in finished version of final report

12/3 Final oral report and presentation of prototype done by Michael

12/5 – 12/20

Conversion of prototype into a lasting, working model

Current Organization of Team Responsibilities:

Vamsi Varra:

Designates team roles and assignments

In charge of maintaining contact with Shannon, the zookeeper

In charge of maintaining the collaboration with Kunal Patel, the electrical engineer who

will be working with us

Aditya Yadavalli

In charge of allocating resources for and obtaining supplies needed for final product

Responsible for final check of group assignments as well as turning them in

Responsible for being most knowledgeable of pertinent safety and regulations

Michael Mathison

In charge of any coding needed for the project

Responsible for being most knowledgeable of patent information

11

Responsible for being most knowledgeable of market analysis

References:

"A Captive Behavioral Enrichment Study with Asian Small-clawed River Otters (Aonyx

Cinerea)." - Foster-Turley. N.p., n.d. Web. 19 Sept. 2014.

DragonflyTV . Episodes . Living Things . Tigers and Otters | PBS KIDS GO!" DragonflyTV .

Episodes . Living Things . Tigers and Otters | PBS KIDS GO! N.p., n.d. Web. 19 Sept. 2014.

"Environmental Enrichment with Zoo Otters." N.p., n.d. Web. 19 Sept. 2014.

"Here Are Some of the National Zoo's Otters Playing a Keyboard."PEOPLE.com. N.p., 30 May

2014. Web. 19 Sept. 2014.

"North Carolina Aquariums » River Otters." North Carolina Aquariums River Otters Comments.

N.p., n.d. Web. 19 Sept. 2014.

AZA Small Carnivore TAG 2009. Otter (Lutrinae) Care Manual. Association of Zoos and

Aquariums, Silver Spring, MD.

Probasco, David John. Evaluation of mercury levels in river otters of northeastern Texas.

Thesis, Tarleton State University. (Publication No. [1486575]).

Cox, Christopher. "Questions and Answers: In-Depth Responses." IUCN Otter Specialist Group.

IUCN OSG, 22 June 2008. Web. 12 Sept. 2014.

Stevens SS, Serfass TL. 2008. Visitation patterns of nearctic river otters (Lontra canadensis) at

latrines. Northeastern Naturalist 15(1):1-12.

Carss, David N. “Foraging Behavior and Feeding Ecology of the Otter Lutra Lutra: A Selective

Review.” Hystrix. Scotland, UK: Institute of Terrestrial Ecology. (179-194). 1995 .

Lariviere, Serge and Walton, Lyle R. “Lontra canadesis.” Mammalian Species. American Society

of Mammalogists. Ed 587 (1-8). 1998.

12

13