Species Identification

1. Introduction

• Purpose: Develop skills for identifying UK marine mammals in the field.

• Species discussed:

  • Two native seals (Phocidae): Grey Seal & Harbour/Common Seal

  • Small cetaceans: Harbour Porpoise, Common Dolphin, Bottlenose Dolphin, White-beaked Dolphin, White-sided Dolphin, Risso’s Dolphin, Striped Dolphin

  • Large cetaceans (whales): Pilot Whales, Killer Whale, Beaked Whales (Mesoplodon spp.), Sperm Whale, Right Whale, Fin Whale, Sei Whale, Minke Whale, Blue Whale, Humpback Whale

• Tools for learning:

  • Observation, silhouette analysis, colouration, size, dorsal fin shape.

  • Behaviour patterns — surfacing, diving, group behaviour.

  • Video examples, quizzes, and ID guides.

2. Seal Identification

Species in UK Waters

1. Grey Seal (Halichoerus grypus)

2. Harbour/Common Seal (Phoca vitulina)

Both are found around North Wales, but Grey Seals are dominant.

Key Distinguishing Features

Field ID Tips

• Observe head shape, nostril pattern, and coat markings.

• Young grey seals can resemble common seals — check forehead slope and nose shape.

• In colonies, behaviour and body proportions help with distinction.

3. Cetaceans: Small Species

A. Harbour Porpoise (Phocoena phocoena)

• Size: ~1.5 m long (smallest UK cetacean)

• Dorsal Fin: Small, triangular, dark; little curvature.

• Head: Rounded forehead, no beak.

• Colour: Uniform grey-brown above, white below.

• Behaviour:

  • Shy, inconspicuous, short surfacing.

  • Often seen alone or in small groups.

  • Does not bow-ride; minimal jumping.

• Key ID tip: Triangular dorsal fin and subtle surfacing.

B. Bottlenose Dolphin (Tursiops truncatus)

• Size: Large (2.5–3.5 m), robust body.

• Colour: Dark grey upper body, pale belly.

• Dorsal Fin: Tall, curved (“falcate”).

• Beak: Short and blunt.

• Behaviour:

  • Very social; often bow-ride.

  • Powerful leaps; visible white belly during jumps.

  • Coastal and offshore ecotypes exist:

    • Coastal: larger, stockier.

    • Offshore: slimmer, lighter grey.

• ID Tip: Curved dorsal fin, stocky shape, and frequent aerial behaviour.

C. Common Dolphin (Delphinus delphis)

• Size: ~2–2.5 m, slender.

• Distinctive Markings:

  • “Hourglass” or “criss-cross” cream/yellow pattern on flanks.

  • Dark grey cape on top, lighter underside.

• Beak: Long and slender.

• Dorsal Fin: Curved, central on back.

• Behaviour:

  • Very active; frequent leaping.

  • Travels in large, fast-moving groups.

• ID Tip: Hourglass flank pattern and energetic group jumps.

D. Striped Dolphin (Stenella coeruleoalba)

• Range: Becoming more common as range expands northward.

• Markings:

  • Distinct black stripes running from eye to anus and along sides.

  • Pale or white underside.

• Beak: Shorter than common dolphin.

• Behaviour: Often mixed with common dolphins; energetic leaper.

• ID Tip: Lateral stripes and shorter beak distinguish it.

E. White-beaked Dolphin (Lagenorhynchus albirostris)

• Range: North Sea, colder temperate waters.

• Size: 2.6–3 m, stocky build.

• Colour: Dark grey with white flanks and white patch behind dorsal fin.

• Beak: Short, white-tipped.

• Dorsal Fin: Curved, broad-based.

• Behaviour:

  • Often in groups; bow-riding common.

• ID Tip: White patch behind dorsal fin and pale beak.

F. White-sided Dolphin (Lagenorhynchus acutus)

• Similar to white-beaked dolphin but:

  • Slightly smaller, more slender.

  • Yellow or cream tinge in flank patch.

  • Dark beak, not white.

• Habitat: Offshore, cold temperate waters (NW Scotland, N Atlantic).

• ID Tip: Yellow tinge on flank and short dark beak.

G. Risso’s Dolphin (Grampus griseus)

• Size: Up to 4 m.

• Head: Rounded with vertical crease (“melon”).

• Colour: Dark grey when young, becoming white or scarred with age.

• Markings: Extensive scarring from teeth of other Risso’s dolphins.

• Dorsal Fin: Tall, curved; noticeable.

• Behaviour:

  • Slow, deliberate surfacing.

  • Social; travel in small groups.

• ID Tip: White, scarred adults and tall dorsal fin.

4. Medium and Large Dolphins / Small Whales

A. Long-finned Pilot Whale (Globicephala melas)

• Family: Delphinidae.

• Size: 4–6 m.

• Colour: Uniform black/dark grey.

• Head: Bulbous forehead, short beak.

• Flippers: Long and pointed backward (key ID trait).

• Social Behaviour:

  • Tight social groups, often seen mass stranding together.

  • Spyhopping behaviour (lifting head above water).

• Difference from short-finned: Long-finned found in temperate regions; short-finned in tropics.

B. Killer Whale / Orca (Orcinus orca)

• Size: 6–8 m.

• Distinctive Colouration:

  • Black with white patches near eye and under chin.

  • Grey “saddle patch” behind dorsal fin.

• Dorsal Fin:

  • Very tall and triangular in adult males (up to 1.8 m).

  • Curved in females and juveniles.

• Behaviour:

  • Highly social, live in pods.

  • Spyhopping, breaching common.

• Diet: Fish, seals, other cetaceans depending on ecotype.

• ID Tip: Contrasting black-and-white pattern and large dorsal fin.

5. Beaked Whales (Family Ziphiidae)

General Features

• Rare, deep-diving, elusive.

• Small dorsal fins far back on the body.

• Bulbous forehead (“melon”).

• Often have pair of visible teeth in adult males.

• Difficult to see due to cryptic behaviour.

Species Examples

• Cuvier’s Beaked Whale (Ziphius cavirostris):

  • White head, dark body.

  • Prominent “dent” or depression behind melon.

  • White scars (especially on males).

• Sowerby’s Beaked Whale (Mesoplodon bidens):

  • Long, slender beak.

  • Northern temperate distribution.

• Key ID Tip: Tooth position (if visible), head depression, and colour patterns.

6. Large Whales (Baleen and Sperm Whales)

A. Sperm Whale (Physeter macrocephalus)

• Type: Toothed whale.

• Size: Up to 18 m (largest toothed species).

• Head: Massive, box-shaped, ~1/3 of body length.

• Blowhole: Single, angled blow to left side.

• Skin: Wrinkled appearance.

• Behaviour:

  • Deep diver; flukes up before long dives.

  • “Square head” easy to recognise.

• ID Tip: Asymmetric blow + massive square head.

B. Right Whale (Eubalaena glacialis)

• Features:

  • No dorsal fin.

  • Callosities (white crustacean patches) on head.

  • Very arched jawline and huge mouth.

• Behaviour:

  • Surface feeder (skim feeding).

• Status: Critically endangered; rare in NE Atlantic.

C. Blue Whale (Balaenoptera musculus)

• Size: Largest animal on Earth (up to 30 m).

• Blow: Very tall (up to 10 m).

• Colour: Bluish-grey, mottled.

• Dorsal Fin: Very small and far back.

• Behaviour:

  • Surface blow, deep dive with large fluke.

• ID Tip: Gigantic size and faint mottling.

D. Fin Whale (Balaenoptera physalus)

• Second largest species (~24 m).

• Colour: Asymmetrical jaw (right side lighter).

• Dorsal Fin: Prominent, back 2/3 along body.

• Blow: Tall and columnar.

• Behaviour: Fast-moving, often travels alone or pairs.

E. Sei Whale (Balaenoptera borealis)

• Medium-large (up to 20 m).

• Dorsal Fin: Tall, slender, positioned near rear.

• Head: More pointed than fin whale.

• Blow: Bushy; moderate height.

• ID Tip: Slender, smaller, and faster than fin whale.

F. Minke Whale (Balaenoptera acutorostrata)

• Smallest baleen whale (~8–9 m).

• Colour: Dark grey with white flipper patches.

• Dorsal Fin: Tall, curved, mid-body.

• Behaviour:

  • Often solitary; surfaces briefly.

• ID Tip: White flipper patch and pointed snout.

G. Humpback Whale (Megaptera novaeangliae)

• Size: 12–16 m.

• Head: Knobbly tubercles; long flippers (1/3 body length).

• Colour: Black above, white below; white tail underside.

• Dorsal Fin: Small, set on a hump-like ridge.

• Behaviour:

  • Highly acrobatic: breaching, tail-slapping, pectoral slaps.

  • Distinctive fluke shape — each individual identifiable.

• ID Tip: Long flippers and energetic surface activity.

7. Blow Characteristics (Useful at Distance)

8. Tail Fluke Patterns

• Useful for individual ID in large whales (humpbacks, sperm whales).

• Shape, notch depth, and scars are diagnostic.

• Minke whales rarely show tail flukes; humpbacks always do during dives.

9. Summary Table of Key Species Traits

10. Key Takeaways

• Field ID relies on a combination of morphology + behaviour + context:

  • Dorsal fin shape

  • Blow type

  • Colouration & markings

  • Size & group structure

  • Habitat (inshore vs offshore)

• Observation patience is vital — species may appear briefly.

• Photographic catalogues help confirm identification.