Tails From The Zoo

Tale of a Wandering Spider November 7, 2009

In early May, 2009 a story was released by the Russell Banner’s Terrie Welwood about a highly venomous spider — the Brazilian Wandering Spider — from tropical America, which arrived in a box of bananas at an IGA grocery store in Russell, Manitoba.  Through the efforts of a number of people, the 2.5-cm-long spider with long legs and red hairy fangs made its way to the Assiniboine Park Zoo.  Considering that the fear of spiders (arachnophobia) is almost universal, it is remarkable that a chain of individuals cared enough about this little wandering stowaway to ensure that no harm came to it after surviving its over-4000-km trip from the tropics.

The spider appears to have started its journey by hiding in a load of bananas in Guatemala, and then being transported to Manitoba.  The box of bananas was ultimately shipped to the IGA in Russell, where one night it left its refuge to search for prey.  A cleaning-staff member discovered the spider and succeeded in trapping it in a container.  He handed it over to the Produce Manager, who then in turn gave it to the Major Pratt High School 12th-grade biology class for study.  Using the resources of the internet, the students took up the challenge of identifying it, and they came to the startling conclusion (based on its size and striking red fangs) that it was a venomous Brazilian wandering spider (a species of Phoneutria; Greek name for “Murderess”), the bites of several species of which have resulted in the deaths of small children and seniors in Amazonia.  Although the bites of these spiders are highly sensationalized as the most-venomous and painful in the world, venom is often not released, or is delivered in such small doses that it is insufficient to kill most human victims.

Red-fanged spider

Photo by Darlene Stack

 

Amid stories in the media, the spider was passed on by one of the students to two Manitoba Conservation staff, and with the recommendation from a Canadian Wildlife Service officer, they delivered the spider on May 8th to the Assiniboine Park Zoo for safe-keeping.  It was set up securely in a terrarium for public viewing in the Tropical House by zookeepers experienced in maintaining spiders. Until its identification could be confirmed, it was treated as a potentially dangerous specimen.  When offered a cricket as food, the spider instantly captured and then devoured the insect, so the spider appeared to be in good health after its long journey.

Zoo Curator Dr. Robert Wrigley contacted Dr. Terry Galloway at the Entomology Department at the University of Manitoba, who recommended he speak to Canadian spider specialist Dr. Robb Bennett with the British Columbia provincial government.  Dr. Bennett acknowledged that spiders are easily misidentified, and while this specimen might be a Phoneutria, it was far-more likely to be a harmless species of wandering spider called Cupiennius, a species of which also has the red hairs on the large fangs.  These spiders have been known to be transported in fruit to other North American cities (e.g., Tulsa in March, 2008), where they are usually misidentified by local spider experts as the venomous Phoneutria.  Other large stowaway spiders (e.g., wandering and black-widows) have been turned over to the Zoo and the J.B. Wallis Museum of Entomology (University of Manitoba) over the years, mainly deriving from shipments of produce.  This Manitoba specimen will be submitted to a professor at the University of California at Berkeley, who is preparing a paper on accidental shipments of exotic creatures.  The huge volume of cargo being transported around the world generates frequent opportunities for invasive pests to reach new continents, where they often cause enormous damage to native ecosystems and national economies (e.g., agriculture, forestry).

Manitoba is host to about 700 species of spiders, which occupy almost all terrestrial habitats and some aquatic ones as well.  They play major roles as predators of insects and other small organisms, and serve as food for songbirds and many other kinds of animals.  All Manitoba spiders carry venom to immobilize and digest prey, but none is dangerous to humans, although the bite of a few species can be painful and cause a local irritation or mild allergic reaction.  The public is encouraged to leave spiders alone to carry out their natural lives, and to not destroy them out of needless fear.

In the autumn, many people are alarmed to discover an impressively large spider (with two bumps on the abdomen) in a web around the home, resulting in a call to the zoo, a university, Manitoba Museum, or Insect Control (City Of Winnipeg).  This is usually the Jewel Spider (Aranaeus gemmoides), the females of which have a respectable head-body length of up to 15 mm.  One of western Canada’s largest orb-weaver spiders, it is docile and only bites if repeatedly provoked.  D.Wade from Insect Control noted that by September, the female has mated with the smaller male, and is looking for a secluded site to deposit her egg case, which may contain 800 fertilized eggs. It appears that houses are a preferred site for stashing the egg case.  The female dies and the cold-hardy eggs over-winter, then hatch with the warming days of spring.  On a sunny day, each tiny spiderlings releases a strand of silk and parachutes away on the wind, to renew the species’ cycle of life.

By Dr. Robert E. Wrigley

Curator, Assiniboine Park Zoo

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Buzzword Biodiversity May 22, 2009

By Dr. Robert E. Wrigley, Curator, Assiniboine Park Zoo, Winnipeg

Biodiversity is a relatively new word in the conservation arena, and as broadly interpreted refers to the number of species in, or biological richness of, an area. In spite of biological inventories and diverse studies carried out over centuries over much of the planet, our knowledge of the natural world remains in its infancy, particular in distant and hazardous locations (e.g., sea floor). As biologists working in such facilities as museums, universities, provincial/territorial wildlife departments, zoos, aquariums, and conservation organizations, we tend to believe we have a reasonable grasp of the biodiversity in our area or province, but do we really? Could we list the taxa in our district, or even on the properties where we live and work?

We generally know what the larger and easily observed species of wildlife are, or the species in our areas of specialty, but this is just the tip of an enormous wealth of life forms of which we know literally nothing, with most species not yet even named and described. This is a serious omission in our knowledge base if we are truly to protect our local biodiversity, ecosystems, environment, and specific habitats. When we attempt to modify species’ populations, distributions (e.g., using exotics for biological control), habitats, and even genes, to support a species-at-risk or one of special interest (e.g., crops, commercial resource harvesting or recreational hunting/fishing), have we any idea what resulting waves (e.g., effects on numbers and gene frequencies of other biota) reverberate through the entire ecosystem? And yet at this time of greatest need for data, taxonomists and ecologists are declining in numbers due to lack of training and job opportunities (linked to funding priorities).

These dilemmas set me to thinking what I could contribute to the biodiversity knowledge of my home province – Manitoba. And so I have, with all naivety and modesty, attempted the impossible – a first crack at a biodiversity inventory of this province. I greatly appreciate the contributions to this effort of my colleagues, whom I placed in the uncomfortable and challenging position of coming up with their best estimates. Hopefully others will be encouraged to generate or update inventories in their districts, and to enlarge their concept of local biodiversity and conservation requirements.

Manitoba hosts five major life zones or biomes – Grassland, Boreal Coniferous Forest, Arctic Tundra, Freshwater, and Arctic Marine biomes, plus Aspen Parkland, Eastern Deciduous Forest, and Forest-Tundra transitions. Each of these major biological communities teems with countless numbers of diverse species, from huge whales, Lion’s Mane Jellyfish and the 7-metre Greenland Shark in Hudson Bay to bizarre microscopic life forms in the soil, water and air, and even in and on our bodies. Manitoba is truly buzzing with life during all seasons, even under the snow and ice.

Glaciers completely scoured the entire province of life about a dozen times in the last 1.5 million years – the Pleistocene Ice Age – which ended only 8,000 years ago. Yet Manitoba currently harbors all five kingdoms of life (plus Viruses) – Bacteria, Protoctista (microscopic protozoans and types of algae), Fungi, Plants and Animals. The larger types of animals and plants have received considerable attention and are more-readily studied, so their numbers are reasonably well known. However, species estimates for most other groups are only recently becoming available (see Table 1).

There are 635 vertebrate (back-boned) animals, over 31,000 invertebrates (“lower” animals), 2433 plants, 800 lichens (a symbiotic association of fungi and algae), 3000 fungi, and a staggering 36,000 algae in Manitoba; certain of these figures will continue to rise with new studies. There are no numerical estimates for other groups, such as protozoans, bacteria or viruses (The latter two are capable of rapid genetic change.), but they exist in Manitoba in the tens or hundreds of thousands of species or types. While mostly unknown, they form the supporting base of complex food webs, are integral to the cycling of matter and energy, and maintain conditions for life on our Earth.

The diversity of life in Manitoba is always changing over time, both in the short term and over the geological time frame. This occurs due to many factors in Nature, such as varying climate, sea level, species’ distribution, relationships with other species, and even bolide-impact events (i.e., meteorite, asteroid, comet). While earlier times (e.g., 10,000 years ago) witnessed the extinction of dozens of large mammals and birds in our region, only 10 species are officially (CDC Nature Serve) recognized as having been lost from Manitoba during historic times, either from extinction, like the Passenger Pigeon and Rocky Mountain Locust, or extirpation (i.e., survives elsewhere) such as the Swift Fox and Whooping Crane. An additional 25 species have not been detected for several decades and may be extirpated, while many other invertebrates have likely disappeared with the loss of native grassland.

To date, 1.75 million species have been named worldwide, and likely over 100 million species (mostly insects and microscopic forms) await discovery. Yet this is but a tiny fraction of the incredible biodiversity (countless billions) that has evolved over the last 3.6 billion years of life on Earth. So how many species are alive now in Manitoba? No one will ever be able to answer this question, but the number may exceed half-a-million. This rich biodiversity interacts within the various ecosystems of our province, generates our life-support systems, and supports our economy and standard of living. On the local level and worldwide, it is to our great advantage to support the conservation of all wildlife and to protect our environment.

Table 1. Recorded or Estimated Biodiversity of Manitoba

This table includes estimates of Manitoba’s current biodiversity (#’s of species) as well as historically extinct, extirpated, and exotic species (*). Estimates become less accurate with diminishing body size and lack of research. Species estimates for many other life forms remain unknown.

ANIMALS
Mammals 88
Birds 391
Reptiles 8 (Snakes 5, Lizard 1, Turtles 2)
Amphibians 16 (Frogs 8, Toads 4, Salamanders 4)
Fish 132 (freshwater 91, marine 41)
Arthropods 25,000 (A few groups of these joint-legged invertebrates are listed here.)
Ticks 15
Mites 5000
Lice 500
Pseudoscorpions 20
Centipedes 50
Millipedes 10
Crustaceans 200
Spiders 700
Insects 18,000
Springtails 200 Mayflies 80
Stoneflies 40 Caddisflies 200
Aphids 400 Midges 300
Thrips 60 Mosquitoes 50
Butterflies 111 Flies 6000
Skippers 33 Fleas 57
Moths 600 Leafhoppers 400
Beetles 2500 Treehoppers 41
Ants 81 Grasshoppers 68
Wasps 5000 Crickets 8
Bees 225 Dragonflies and Damselflies 100
Bugs 1400
Tunicates 18
Sea Squirts 16
Larvaceans 2
Molluscs 170
Snails 94
Clams and Scallops 72
Chitons 3
Tusk Shell 1
Rotifers 50
Water Bears (Tardigrades) 30
Roundworms 3000
Flatworms 3000 (land, freshwater and marine)
Annelid Worms
Earthworms 120 (including 100 freshwater and terrestrial ones & 20 marine)
Bristleworms 85
Leeches 24
Comb Jellies 3
Cnidarians (Jellyfish, Anemones, Soft Corals) 57
Sponges 5
Arrow Worms 3
PLANTS
Vascular Plants (Flowering Plants and Ferns) 1700 (native 1500, exotics 200)
Mosses 733
LICHENS 800
FUNGI 3000
PROTOCTISTANS (Unicellular protists) (Unknown, but in the hundreds of thousands)
Algae 36,000
BACTERIA and VIRUSES (Likely in the hundreds of thousands

*Species Estimates by:
Dr. Robert Wrigley (mammals, reptiles, amphibian, invertebrates), Rudolph Koes (birds), Dr. Ken Stewart and Dr. Bruce Stewart (fishes), Dr. Terry Galloway (arthropods), Dr. Eva Pip and Dr. Bruce Stewart (molluscs), Dr. Bruce Stewart (marine invertebrates), Dr. David Punter (fungi), Dr. Diana Bizecki-Rodson (vascular plants), Dr. Michele Piercey-Normore (mosses, lichens), Dr. Gordon Robinson (algae).

References

  • Hamel, Cary (pers. comm.) Nature Conservancy of Canada, Manitoba Region, and the Manitoba Conservation Data Centre.
  • Stewart, DB, and W.L. Lockhart, 2005, An overview of the Hudson Bay Marine Ecosystem, Can. Fish. Aquat. Sci. 2586. A remarkable inventory of the little-studied ecosystems of Hudson Bay.
  • Wrigley, R.E. 2007. Zoological Author and Editor, The Encyclopedia of Manitoba. Great Plains Publications, 814 pp. The most-current and comprehensive information on Manitoba biodiversity.
 

Exotic Animals in Manitoba May 19, 2009

Filed under: Biodiversity,Eco-Dates — Scott Gray @ 4:47 am
Tags: ,

By Dr. Robert E. Wrigley, Curator, Assiniboine Park Zoo, Winnipeg

Exotic animals are species inhabiting Manitoba that arrived through the activities of humans, although the line blurs in cases where humans have altered the landscape to the degree that has permitted the apparently recent entry and establishment of dispersing non-native wildlife (e.g., white-tailed deer) following the advent of agriculture. With the great natural dispersal abilities and adaptiveness of small life forms, countless organisms have invaded the province since the historical period, from viruses like West Nile to injurious insects such as the elm bark beetle, which carries the virulent fungus causing dutch elm disease.

Exotics have also been used widely for agricultural purposes such as all crops, and pollinators (e.g., the alfalfa-pollinating leafcutter bee, Megachile rotundata), in pest control (ladybird beetles to devour aphids), and to attack invasive exotic plants (flea beetles to eat leafy spurge and purple loosestrife). And of course, livestock species (horses, cattle, pigs, goats, sheep, llamas, alpacas, chickens, turkeys, etc) are all exotics, often displacing native wildlife over immense regions. These domestic animals also broadcast weed seeds in their droppings and carry their share of non-native diseases, which all-too-often are transmitted to native wildlife (e.g., anthrax and bovine tuberculosis). The threat of reverse infection, such a tuberculosis-infected elk infecting cattle raised in the same area has devastating consequences for both wild populations and the ranching industry, leading to calls for the culling and even eradication of the wild animals, even in conservation areas like Riding Mountain National Park.

No one has any idea how many non-native species of invertebrates (lower animals without a backbone) have been accidentally introduced and become part of the local fauna of Manitoba, but they no doubt number in the thousands. For example, the introduced pharaoh ant (Monomorium pharaonis) lives only inside heated buildings, thereby avoiding the cold of winter. Earthworms (There are no native species), slugs, and other invertebrates are particularly common in disturbed areas (e.g., city yards). The cabbage white butterfly (Pieris rapae) was accidently introduced from Europe to Quebec about 1860, and has become the most-common butterfly in Manitoba, found in gardens, crops, and forest clearings as far north as Churchill.
There are 12 exotic species of fish in Manitoba, introduced purposefully for sport fishing, or accidentally – common carp, goldfish, rainbow smelt, cutthroat trout, rainbow trout, Koakanee salmon, brown trout, splake (Lake X Brook trout hybrid), tiger trout (Brook X Brown trout hybrid), white bass, smallmouth nass, and largemouth bass. Quite likely others will be added to this list in the future through accidents, illegal release, or connecting of drainage systems (i.e., the Missouri system into the Red River in North Dakota).

Over 100 species of birds have been released into North America, but fortunately most of these failed to become established. A few, like the cattle egret from Africa and Eurasia, has spread throughout the New World on its own (with cattle ranching supporting the birds once here), and occurs sparingly in Manitoba during the summer. Others were released by conservation departments and game associations for hunting opportunities, such as grey partridge, ring-necked pheasant and wild turkey – the latter two usually requiring supplemental food to survive a number of Manitoba winters. The release of the house sparrow, starling, and rock dove (pigeon) in the United States in the late 1800s has caused unimaginable damage to ecosystems throughout North America. These birds devour huge amounts of natural and human foods, confiscate nesting sites formerly utilized by native species, and foul food supplies and human structures with their droppings.

Among the mammals, the house mouse and Norway (brown) rat are the supreme invaders, having colonized the entire world (except Antarctica) wherever humans have travelled. These two pests spread out in summer throughout Manitoba into natural habitats, agricultural fields, and in urban alleys, but must retreat to human shelter for the winter period. Both these Old World residents invaded Manitoba first at Churchill via ships of the early explorers, whalers and traders, and their descendants still survive there in buildings and on upper beaches in summer to this day — well over three centuries later (forts were established by 1670).
Prehistoric humans first arrived into southwestern Manitoba about 8,000 years ago, soon after dry land was exposed from the melting Laurentide Glacier and floodwaters of Glacial Lake Agassiz. Immigrating about 15,000 years ago from eastern Asia, these hunter-gatherers (with ever-advancing cultures and technologies) may also be viewed as a foreign element, in that they invaded an unoccupied continent. However, our species arrived here through natural dispersal (as did thousands of other wildlife species) over a temporary land bridge (Beringia), and hence this case does not fit the definition of exotic. The appearance of humans had major repercussions in many North American ecosystems, mainly through hunting activities (with weapons and use of fire). Humans contributed to the sudden extinction (from 12,000-8,000 years) of over one-half the continent’s large species of mammals and birds.

Releasing any foreign species of plant, animal, or other biota into the wild is biologically indefensible and generally results in unforeseen negative consequences. While some introduced species have failed to become established, the successful invaders invariably out-compete similar native species, outright devour them, or introduce foreign-disease organisms. At the very least, they occupy habitat of native species, seldom providing significant food, cover, or other resources for native wildlife. It is naive and uniformed, whether instigated by a conservation department or a private person releasing an unwanted pet, to think that such a release will be a positive step for the organism, the species, or the biotic community, and yet the practice continues. The problem may sometimes be compounded by introducing an exotic natural predator of an exotic pest, as is the current practice in biological control. While occasionally this proves helpful in reducing (not eliminating) the primary pest, the fact remains that an additional exotic has been introduced, often without full knowledge of long-term effects on the ecosystem.

The release or escape of genetically modified varieties of crops and other organisms are exotics of major concern, since the results frequently have far-reaching effects, including the real possibility of altering the genetics, ecology, or even the survival of wild species. While no doubt a boon to food production and company profitability, transgenic (recombinant-DNA) technology carries inherent risks for species, ecosystems and human health. This is a contoversial issue, with many known and unknown factors to consider. Most countries, including Canada, have embraced this technology (or will in time), since economics and food production are always viewed a higher priority than ecosystem health and wildlife conservation. With increasing and rapid international shipping of goods and travel of people, thousands of additional exotics (from viruses and bacteria to vertebrates) will be introduced to North America and Manitoba in the future. One can only guess what the impacts of all these changes will be on our native biotic communities and on human health.