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Suffolk Natural History, Vol. 60
CRYSTAL SEA SLUG ANTIOPELLA CRISTATA (ORDER NUDIBRANCHIA; FAMILY JANOLIDAE) AT WALBERSWICK, SUFFOLK JIM R. ELLIS The sea slug Antiopella cristata (Delle Chiaje, 1841), formerly Janolus cristatus and sometimes referred to as the ‘crystal sea slug’ or ‘crested aeolis’, is distributed widely in the shallow sublittoral of the eastern North Atlantic. It has been reported from the southwestern coast of Norway (e.g. at Tananger and Egersund; Evertsen & Bakken, 2005) to Morocco and the northwestern Mediterranean Sea (Thompson & Brown, 1984). It is generally found from the shallow sublittoral down to 40 m water depth (Thompson & Brown, 1984) but has been reported at 70 m water depth in the Mediterranean Sea (Toma et al., 2022). Whilst it has been recorded widely around the British Isles, most of these records have been from along the southern and western coasts (e.g. Alder & Hancock, 1845– 1910; as Antiopa cristata), and records from the eastern seaboard have generally been from the northern North Sea (Seaward, 1990; Thompson & Brown, 1984). Whilst not listed for Norfolk by Hamond (1972), data submitted to the National Biodiversity Network Atlas (https://nbn.org.uk/) indicate a moderate number of records from the north Norfolk coast, but seemingly only seven records from the coasts of Essex and Suffolk (Table 1). It has also been reported from other coasts of the southern North Sea, such as Den Helder in the Netherlands (Engel, 1936). Table 1. Records of the sea slug Antiopella cristata along the coasts of Suffolk and Essex, ranked chronologically. Previous records from the National Biodiversity Network Atlas (https://nbn.org.uk/) Site
Latitude
Longitude
Date
No.
Sizewell
52.1973
1.6387
12/06/1993
-
Wreck of the “Alto”
52.4217
1.8172
20/06/2009
-
Wreck of the “Fontenoy”
52.4986
1.9389
22/08/2010
-
Lowestoft (marina)
52.4714
1.7539
22/08/2010
-
Wrabness (Essex)
51.9474
1.1622
01/05/2014
-
River Blackwater (Essex)
51.7351
0.8554
19/09/2014
-
Lowestoft (children’s corner beach)
52.4710
1.7554
20/06/2017
-
52.3141
1.6726
07/08/2024
8
21/08/2024
1
Walberswick (harbour wall)
Source
https:// nbn.org.uk/
Present study
Antiopella cristata has several characteristic features: it has a slightly translucent body, with larger individuals having a brown hue and white flecks. It has elongated cerata that surround the body (including around the anterior of the body), each having a narrow dark thread (digestive gland) and a blue-white tip. Additionally, there is a caruncle visible between the rhinophores (Picton & Morrow, 2023).
Trans. Suffolk Nat. Soc. 60 (2024)