Dlamini, L.N2449510@uwc.ac.zaBSc. Envronmental scienceBCB 311Dr. R. Knight03 April 2006

Available at http://planet.uwc.ac.za/nisl/Eco_people/Presentations/

Eutherian mammals

Insectivores –primitive placentals

AimAim

Determine why insectivores are considered primitive.

Look at their conservation status and their threats

Understand what makes every family in the order so unique.

How humans have affected insectivores

IntroductionIntroductionThe presentation will be on the order Insectivores.

We will establish why they are considered primitive as well as look at the primitive characteristics.

They are small mammals that are so called after what their diet consists of mainly “insects”.

They are also the most ancient placental mammals, having been around since the upper cretaceous period.

Most are tropical species and hence are found throughout the world except regions like Australia, South America and Polar regions.

Insectivores are diverse with 7 families,68 genera and 439 species. They are considered to be the most primitive of the eutherian mammals.

What are insectivores?

• Size – being small

• Plantigrade locomotion

• Small braincase

• Primitive dentition

• Presence of cloacae

• Minute size of ears and eyes

Primitive features

• TalpideaTalpidea

• ErinaceidaeErinaceidae

• ChrysochloridaeChrysochloridae

• TenrecidaeTenrecidae

• NesophontideaNesophontidea

• SolenodontidaeSolenodontidae

Families in the order:

Family: Solenodontidea• Consists of 1 genus.• Found In west Islands• The size of a guinea pig.• Lives on invertebrates and fruit.• Its form of defence is venomous saliva.• It is on the verge of extinction.• The picture is of a solenodon cubanas.

Family: Tenrecidae Consists of 24 species and 10 genera. Found in Madagascar. The size of a rabbit sometimes. Lives on ivertebrates. Defend themselves by using spines. Conservation status not clear.

Family: Chrysochloridae

Are famously known as the golden moles. Found in the southern half of Africa. They are inactive during winter. They live in sand dune regions. Lives on legless lizzards. Consists of 18 species.

Family: Erinacidae They are found in continents Europe, Asia and

Africa.commonly known as the hedgehogs. Are covered with spines. Adapt to the most complex habitats. Solitary creatures except in mating seasons. They eat almost anything. Are quite resistant to poisons. Have 21 species.

Family: Soricidae They are very small ,the largest is the size of a

rat. The family hosts shrews,mole and desmans. Found in asia, africa, north and south America. Are terrestrial and aquatic. Some of their bites are vernoumous kills or

paralyses prey.

Family: Talpidae It’s the mole family. 42 species. A true zygomatic arch in the skull. Are subtaranean species. Are burrowing creatures. Salivary glands produce a toxic substance

for defence.

Family: Macroscelididea Non social creatures. Large eyes and long legs. Mouse sized, alret and agile creatures Live on ants and othe invertebrates. Diurnal creatures.

Importance of insectivores Have no or little economic value today. Mostly used in research as guinea pigs. Small mammals shape the environment or

landscape.

Treats:Humans & insectivores• Man has changed the landscape.By clearing

forests thus leaving insectivores vulnerable to prey.

• Mankind has also hunted them down in some decades to make coats with their fur.

• Man has contributed heavily in climate change thus changing environments that were prevously favourable to harsh conditions.Urbanisation.

• Because they are small they mega herbivores trample on them.

• Human encroachment.

Conclusion

• Insectivores are indeed the most ancient and primitive placentals.

• Their minute evolution was during the cretaceous period 125 million years ago.

• They are only distributed in mostly Terrestrial areas which they are specialised for.

• Their succsess could be attributed to their diet of insects.

• Their main threat is land clearance.

References www.thewebsiteofeverything.com -for the

pictures www.life.umd.edu/classroom/bsci338/lectu

re/insectivores.html www.ncbi.nim.nih.gov/entrez/query.fcgi?c

md=retreive Boliere.F. The natural history of mammals

3rd edition.(1964), Alfred .A. Knopf inc, Paris, 390pp.

References cont. Campbell.N.A. Biology 3rd edition(1987),

the Benjamin/Cummings publishing company inc. Carlifonia, 1190pp

Boliere.F. Mammals of the world,(1955), Gearge.G. Harrod & co LTD. London, 223pp

Mathews.L.M. The life of mammals vol 2, (1971), Unwin Bros. Ltd. Hampshire, 340pp