ID GuideMarine non native species

A large, golden-brown kelp

Key ID features:� 1-3m in length, consisting of a

divided frond with a mid-rib

� very frilly with lots of “ribbons”just above the root-likeholdfast

� has a long stipe

Similar to: native kelpssuch as Saccorhiza polyschideswhich does not have a mid-riband has a knobbly, bulbous -holdfast

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WakameUndaria pinnatifida

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Orange-striped anemoneHaliplanella lineata

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Darwin's barnacleElminius modestus

A barnacleKey ID features:� small cone shaped shell up to

1cm across

� white-grey in colour

� Diamond shaped opening

� shell has 4 plates

Similar to: Semibalanus balanoides, which also has adiamond-shaped opening. Elminius modestus can be positivelyidentified by only having four outer shell plates, other specieshave six

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Please report your sighting on the Marlin website www.marlin.ac.uk/rml or phone 01752 633291

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WireweedSargassum muticumA type of brown seaweed

Key ID features:� A large olive-brown seaweed

with fronds often over 1m long

� A main axis or stipe bearsalternating secondarybranches, giving characteristic“washing line” appearance outof water

� Branches withsmall,flattenedleaflets andspherical gasbladders Jo

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Toothed leaflet

Spherical gas bladders

An anemoneKey ID features:� Up to 4cm tall, (usually 1-2cm)

with a smooth and cylindricalcolumn

� Generally olive green or brownwith contrasting vertical stripes(stripes are usually orange incolour, less commonly yellow or white stripes)

� Up to 100 slender tentacles, these and their supportingplatform greyish

Distinguished by: the vertical stripeson the column. Young specimens ofplumose anemone (Metridium senile)

may be similar ingeneralform, but arenever striped

MCS ID sheet:Layout 1 17/8/11 16:50 Page 1

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Information provided byMarine Biological Association

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Striped barnacleBalanus amphitrite

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Slipper LimpetCrepidula fornicata

Leathery sea squirtStyela clavaA sea squirt

Key ID features:� A brown sea squirt up to 20cm tall

� Attached by narrow stalk(underdeveloped when very small)

� two tube like openings (siphons)on top which have dark brownstripes on the inside

� surface istough andleathery,lookslumpy.

Male

Female

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registered charity no (england & wales): 1004005registered charity no (scotland): sC037480

www.mcsuk.org

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John Bishop / MBA of the Uk

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A barnacle

Key ID features:� A white or pinkish barnacle

growing to 1cm in diameteror more

� Large diamond shapedopening

� six outer shell plates relativelysmooth, with groups of purple orpink stripes tapering from thebase

� four dark bands crosstissue flaps borderingthe opening

A gastropod mollusc – a type ofsea snail

Key ID features:� often found in curved chains of

up to 12 individuals with largeshells at the bottom and smaller

ones ontop

�Domedshell, oval or kindey shaped up to5cm long with distinctive slipper-like internal shelf

�shell can be white, cream, yellowor pinkish in colour, with streaksor blotches of red or brown

Japanese skeleton shrimpCaprella muticaAn amphipod crustacean

Key ID features:� A slender, reddish, shrimp-like

animal

� Males up to 45mm long with twoelongated body segments behindthe head, the hindmost of whichhas a pair of large graspingappendages

� females smaller (to 15mm) withoutconspicuously elongated segments orenlarged appendages, but with redspotted brood pouch on underside

� Both sexes have spines along back

� Larger than native skeleton shrimps

Pacific oysterCrassostrea gigasA bivalve mollusc

Key ID features:� thick, rough, hinged shell up to

18cm long

� Markedly wavy orsaw-toothed shell margin

� shell may have dark purplepatches

Similar to: native oyster Ostrea edulis,which has more numerous but muchweaker ridges and much less wavy shellmargin. Crassostrea gigas tends to bemore elongate in shape whereas Ostreaedulis can be almost circular

A crab

Key ID features:� Large crab up to 8cm across

� Grey-green to dark brown incolour with paler legs, which aretwice the length of the body.

� near-hexagonal body shapenarrowing towards the front

� 4+4+4 pattern of teeth aroundfront end of body and deepcentral notch between the eyes

� Distinguishing feature in adultcrabs is the dense mat of hair onthe claws. the leading edges ofthe legs are also very hairyphiL CrABB/ nAtUrAL historY MUseUM

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Chinesemitten crabEriocheir sinensis

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