Separate orca populations presentation

B Y K A I T L I N P R I N C E

T E X A S A & M C O R P U S C H R I S T I

P R O F E S S I O N A L S K I L L S

B I O L 2 2 0 0 . 0 0 3

Morphological and behavioral differences between separate populations of Orcinus orca

Outline

Overview of O. orca Importance of classification

Definition of species and ecotype

Methods

Conclusion

Discussion

Current Taxonomy

Animalia

Chordata

Mammalia

Cetacea

• Odontoceti

Delphinidae

•Orcinus

•orca

Classified as a dolphin

Common name, “killer whale”, misleading

Most widely distributed species after humans

Classification can effect conservation status

Overview of O. orca

Dorsal Fin

Saddle PatchEye Patch

Adult Male

Adult FemaleJuvenile

Figure 1: Diagram of O. orca (1)

Distribution of O. orca

Fig. 2: Distribution of O. orca (2)

Social Structure of O. orca

Pods: small groups of directly related individuals that constantly travel, hunt and live together

Clans: related pods that have overlapping ranges and occasionally mingle

Communities: sets of clans that regularly intermingle

Species Ecotype

Often defined as a group of organisms capable of interbreeding and producing fertile offspring in the wild

Describes a genetically distinct geographic variety, population or race within species which is adapted to specific environmental conditions

Definitions of Species and Ecotype

Methods: Observations

Morphological differences Size/shape of eye patch

Presence of dorsal cape

Size/shape of dorsal fin

Behavioral differences Feeding patterns

Movement patterns

Group size

Reviewing available photographs

Fig. 3: Type A attacking a minke whale (Pitman, Ensor, 2003)

Type A Type B

Typically feed on minke whales

No cape markings

Medium-sized eye patch

Very large eye patch

Well-defined cape markings

Lighter, grey colored body

Typically feed on seals

O. orca Populations of the Antarctic

Fig. 4: Type A (Pitman, Ensor, 2003) Fig. 5: Type B (Pitman, Ensor, 2003)

Type C Physical Comparisons

Largest pods

Eye patch slanted forward; “smudged” appearance; small, gray body with cape

Typically feed on Antarctic cod

O. orca Populations of the Antarctic cont.

Fig. 6: Type C (Pitman, Ensor, 2003)Fig. 7: Comparison of Types

(http://en.wikipedia.org/wiki/Killer_whale)

Comparison of Type A and Type B Movements

Fig. 11: Comparison of Type A and Type B Movements (Pitman, Ensor, 2003)

Residents Transients

Primarily eat fish

Live in matrilineal pods

More vocalizations

Most extensively studied group

Exclusively eat marine mammals

Typically live in groups of three

Less vocalization; complex dialects

O. orca Populations of the North American West Coast

Fig. 8: Resident dorsal fin (Baird, Abrams, Dill, 1992)

Fig. 9: Transient dorsal fin (Baird, Abrams, Dill, 1992)

Comparison of Residents and Transients

Fig. 10: Differences between residents and transients (Baird, Abrams, Dill, 1992)

Methods: Satellite Tracking

Satellite tracking is a useful way to track individuals

Small dart with transmitter attached

TemporaryFig. 12: Satellite tracking (Russell, Pitman, Ballance, 2008)

Type B Individual Type C Individual

Comparison of Type B and Type C Movements

Fig. 13: Satellite tracking (Russell, et. al., 2008)

Fig. 14: Satellite tracking (Russell, et. al., 2008)

Culture Application to O. orca

Consists of the beliefs, behaviors, objects, and other characteristics common to the members of a particular group or society

Have been shown to teach their young certain behaviors (namely hunting)

Pass on specific dialects from one generation to the next

Behaviors NOT common to all members of the species, only that pod or clan

Definition of Culture and Application to O. orca

Type D (Antarctic)Offshore (North American West Coast)

Identified by mass stranding in New Zealand/handful of sightings

Unknown diet

Extremely small eye patch; bulbous head

Primarily feed on schooling fish

Live far from shore; rarely in shallow waters

Live in large groups of 20-50, sometimes more

Other Possible Groups

Conclusion

Evidence for separate species or subspecies

Morphological differences

Behavioral differences

Geographic isolation

Fig. 15: Type B spy-hopping (Pitman, Ensor, 2003)

Discussion

More information is needed on the lesser known groups

Genetic analysis of populations would provide evidence of reproductive isolation

Important to determine conservation status (endangered)

Fig. 16: Type C mother and calf (3)

References

Baird, Robin. Abrams, Peter. Dill, Lawrence. Possible indirectinteractions between transient and resident killerwhales: implications for the evolution of foragingspecializations in the genus Orcinus. 1992. J. Oecologia.89: 125-132.

Pitman, Robert. Ensor, Paul. Three forms of killer whales (Orcinusorca) in Antarctic waters. 2003. J. Cetacean ResourceManagement. 5(2): 131-139.

Russell, Andrews. Pitman, Robert. Ballance, Lisa. Satellite trackingreveals distinct movement patterns for Type B and Type Ckiller whales in the southern Ross Sea, Antarctica. 2008. J.Polar Biology. 31: 1461-1468.

Image References

(1) http://www.google.com/imgres?imgurl=http://www.acsonline.o rg/factpack/images/KillerWhaleRangeMap.jpg&imgrefurl=http://www.acsonline.org/factpack/orca/kidDistribution.html&usg=__lUmoZMbLL_QUoq3v9uxbWGeenXY=&h=430&w=720&sz=168&hl=en&start=0&zoom=1&tbnid=oOe7Pvao84Mf8M:&tbnh=112&tbnw=188&ei=Ybl3Tc6BDurj0gHC9uSkBw&prev=/images%3Fq%3Dkiller%2Bwhale%2Bdistribution%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26sa%3DX%26rls%3Dorg.mozilla:en-US:official%26channel%3Ds%26biw%3D1366%26bih%3D607%26tbs%3Disch:1&um=1&itbs=1&iact=hc&vpx=117&vpy=111&dur=75&hovh=173&hovw=291&tx=120&ty=114&oei=Ybl3Tc6BDurj0gHC9uSkBw&page=1&ndsp=19&ved=1t:429,r:0,s:0

(2) http://www.acsonline.org/factpack/images/orca-family-med.gif

(3) http://en.wikipedia.org/wiki/File:Type_C_Orcas.jpg