Rockpooling under Worthing Pier  2

by Andy Horton 1994, 1998 & 1999

Rockpooling under Worthing Pier 1994

The sea was flat as a pancake, and bright blue as the sky was clear and sun was shining. The spring tide at Worthing recedes to its maximum around dawn and dusk. A 5.8 metre tide on 14th June 1994 (measured at Shoreham Harbour) was just sufficient to uncover the rock and sand terrain beneath the amusement pier. At first glance, the shore appears exclusively sandy and in all respects one of the  least promising of rockpooling shores. Firm sand leads the explorer out to below mid-tide region where the sand gives away to a mixed ground with rocks buried in the sand, a few looser rocks (cobble-sized), and shallow sandy pools.

Mussel Community

Under the steel girders of the pier is the best area, with the supports providing attachment points of a sizeable mussel community. Mussels are a rich source of food for many animals, and the community including barnacles, provides incidental nutrition and shelter for other communities. Hydroids are are regular epifauna, and colonies of this animal are ideal for viewing under the microscope. Often, other small animals like a small shrimp-like animal Corophium crassicorne and nudibranchs (sea-slugs) are not observed in the wild, and are only discovered when the mussel or rock is introduced into the micro-aquarium. Two minute sea-slugs, the yellow and white Polycera quadrilineata and the red tinged Doto coronata are two species most often found at Worthing. Neither species exceeds 15 mm in length.

Hydroids on a mussel shell, Worthing, Sussex coast, England


However, without the aid of the microscope, the obvious predator on the mussel is the Dogwhelk, Nucella lapillus. Girders are littered with row upon row of orange egg capsules, sometimes grouped together in a bunch, and sometimes more yellowish. This predatory gastropod feeds on mussels and barnacles. This univalve mollusc is prevented from breeding in shallow seas and estuaries polluted by TBT (tribulytin) used in anti-fouling paints on large ships. Five miles to the east at Shoreham Harbour, the Dogwhelk has not been recorded since 1981. Dogwhelks at Worthing are found in various colours including pure white and pure orange, but mostly they are dirty mixture of white and purple.

Sea Anemones

Taking advantage of the pleasant weather, the purpose of the visit in the early hours of the morning, was to have a look around and see what fauna was present. Ten years experience had demonstrated that June is one of the poorest month on the mid-Sussex coast. Species breeding earlier in the year will have returned to deeper water and the planktonic fry will not have settled (with about three* exceptions, or will only just be beginning to settle) in the shore pools.

White Plumose Anemones, Metridium senile, draped down from horizontal wooden supports just elevated from the shore floor. They looked ugly like used condoms, which is in contrast to their puffed out beauty when the hundreds of fine tentacles expand in concentric circles to capture the microscopic plankton. Worthing is an unlikely site for sea anemones, but I have discovered at least 9 different species here. It is particularly noted for Sagartia troglodytes but occurrence is highly variable and on this June day, they had to be searched for. Beadlet Anemones, Actinia equina, are always present but not in large numbers. It is worth noting that there was at least a dozen closely observed green specimens with broken yellow vertical lines on the column and various other yellow dots which made the anemone resemble an under-ripe 'strawberry'. These anemones had been observed over long periods (2 years) and they retain this coloration, with the lines becoming more pronounced as the anemone grows. At least two Snakelocks Anemones, Anemonia viridis, were discovered. They were together, so it is fair assumption that a single specimen had divided into two. This anemone is at the edge of its range eastwards up the English Channel at Worthing where it is regular and sometimes very common. Five miles to the east at Shoreham, the species is occasionally found, and a further 7 miles further to the east at Ovingdean it is exceedingly rare (1 found in over 100 visits).

Hermit Crabs

Trundling over the floor of shallow pools, small Hermit Crabs, Pagurus bernhardus, were the most noticeable mobile fauna. Almost exclusively, they occupied empty shells of the Grey Top, Gibbula cineraria, with one larger specimen in an orange Dogwhelk shell.
 A juvenile Blenny, Lipophrys pholis, (28 mm) sheltered under a small rock, and Sand Goby fry, Pomatoschistus minutus, darted to and fro in the pools. They had not settled yet on their bottom living existence.
 Only one new discovery, though! the Star Ascidian, Botryllus schlosseri. This is not normally resident on the shore in Sussex. It was stranded specimen with the colony living on the Sea Squirt Ascidiella aspersa which itself was fastened to the holdfast of a large wrack. The large seaweed had lifted its rock and had drifted inshore to be washed up and die beneath the pier. 

Worthing Pier September 1998

Approaching the highest tides in living memory (7 metres range at Shoreham-by-Sea on 8 October 1998), I took the opportunity of a rare fine day on 21 September 1998, in the previous spring tide sequence, to get up early in the morning to catch the low spring tide which occur at dusk and dawn on the Sussex coast.

It had been the worse 'rockpooling' year on record (at least 20 years) and after a mixture of sudden heat waves and squalls, the signs were not too promising. But it is after unusual conditions that something unusual can be discovered. However, this was not to be the case, as the small fish and invertebrates were exactly what I expected to find underneath Worthing pier. The workmen had scraped away many of the clumps of mussels attached to the supports. The main affect of this was to reduce the numbers of the resident Dogwhelk population. This gastropod mollusc (marine snail) feeds on mussels (more info.).

Small Pools

Underneath the pier, depressions in the sand and rock, leave shallow pools and a few slightly deeper ones. These pools are occupied by small fish from March onwards, but they only start getting crowded from June onwards. The variety can vary. Usually, the late autumn brings the largest number of different species, although the numbers may be higher in the summer.

Small Fish

The small gobies are not visible immediately as they are camouflaged to match the sand on which they rest. At the first disturbance they will dart in all directions. Normally, gobies do not mix in the same pools, but in these  confining pools for a very short period when the tide was out, the Common Goby, Pomatoschistus microps, was the very common, with hundreds in each pool. They varied in size from 20 mm to 32 mm, when they reach a maximum size of 64 mm of their short life span in the following year. The larger and longer Sand Gobies, Pomatoschistus minutus, were common and could be counted in scores. These fish were measured up to 55 mm in length. They will grow up to 94 mm and these fish are shore inhabitants habitually only in the autumn on the Sussex coast. In the same pools, but more often in tiny pools under rocks, juvenile Rock Gobies, Gobius paganellus, hide.

If the gobies were hard to spot, the juvenile Dragonets, Callionymus lyra, were likely to be overlooked. They buried themselves completely in the bottom of a sand and rock pool, and only if they deigned to reveal themselves by leaving the sand could they then be spotted, by their distinct swimming style, not the quick dartings of the gobies, or the squirmings of the blennies, but slower, and with an ability to turn sharply. They would not panic and dart into the net, but to catch one it is necessary to chase it with a net, keeping an eye on the fish which is cryptically sandy coloured to merge in with the bottom of the pool. These fish looked malnourished and many were very small, only 20 mm up to a few larger specimens of 60 mm.

In the same pool there were juvenile Bass, Dicentrarhus labrax, at least one 5-Bearded Rockling, Cilita mustela, and smallish Long-spined Bullheads, Taurulus bubalis, all fish capable of feeding on these smaller fish. A few Blennies, Lipophrys pholis, occupied the same pool and these were very small, 20 mm, and they could be found under small rocks as well.


Crabs are always present on this shore, but never really abundant, except in some years when small Hermit Crabs, Pagurus bernhardus, could be shovelled up by the bucket load. They were quite frequently to be discovered trundling along the bottom of the pools. This was how the Dragonets were revealed. One of them crawled over the buried the fish,  which then adjusted its position revealing itself. Edible Crabs, Hairy Crabs, Hairy Porcelain Crabs, Long-clawed Porcelain Crabs, were all present (more info.).

Sea Anemones

Worthing is a good site for sea anemones, but the numbers vary considerably. The species Sagartia troglodytes is always present, but numbers were much less than are sometimes present. Sometimes they are buried and cannot be seen. Plumose Anemones were represented by less than a dozen draped on the pier supports. Beadlet Anemones, Actinia equina, and Snakelocks Anemones were there in small numbers. Dahlia Anemones, Urticina felina, were absent.

Other Invertebrates

Sussex is not renowned for its molluscs on the shore. The usual resident Mussels, Periwinkles, Carpet Shells, Grey Topshells and Dogwhelks were common.
A Sunset Shell, Gari depressa, (identification to be confirmed) was discovered buried just beneath the surface.

There were patches of Star Ascidian on rocks and weed.

Worthing Pier    16 March 1999

After a rather gloomy and wet winter, if not particularly cold, it was pleasant to be out in the sun for the warmest day of the year so far. Not that warm, and there was a brisk breeze from the west, so a jersey was necessary. It was the first low spring tide at about 4.30 pm GMT in a run of very low tides up to and after the Vernal  Equinox on 20th March.

Early in the Year

It was really too early in the year to expect anything outstanding, although the sun had already warmed up the pools, and even under the shade of the pier, the water did not feel that thorough chill that would be quite likely in February. It was my first proper rockpooling trip of 1999, and I went straight down to the low water mark at the pier end.


I heaved over a large boulder and laid it carefully aside to avoid squashing something that wriggled. As the puddle underneath cleared and my eyes attuned to the small pool, I simultaneously spotted the unmistakeable appearance of a full grown adult Blenny and a flurry of movement as a bronze 5-Bearded Rockling tried to find new shelter. Almost, in the same instant, my eyes focused on the snake-like coil of a young Butterfish. It was a jump of a second or two, before I could make out the carapace of a young and small Edible Crab, trying to bury in the sand but it could not hide completely.


Some species of crab are regularly found that the absence would be a suprise. Hairy Crabs, Pilumnus hirtellus, were found in pairs under rocks. As their name suggests there legs were covered with hairs. Sometimes if they have been scrabbling about in the silt, picking up morsels with their diffferent-sized claws, the hairs had collected so much muck that their pale crimson colour was obscured. They far outnumbered the Shore Crab, Carcinus maenas, of which no large ones were to be seen, although there must have been small ones amongst the mussel shells. Edible Crabs, Cancer pagurus, were frequently to be discovered under the larger rocks, some one moult away from an edible size. Both species of Porcelain Crabs clung to the underside of rocks. A solitary large Squat Lobster, Galathea squamifera,  shot backwards at speed when the rock was lifted. A few small prawns, Palaeamon elegans, were in the pools, but there were no small goby fish yet it was too early for them.


The resident Grey Topshells and Periwinkles, as well as lots of Dogwhelks and their egg capsules on the pier supports, were to be found as expected.

Onchidoris bilamellata

However, of most interest was the spawn of the small sea slug Onchidoris bilamellata and under rock their was a pair of individuals preparing to spawn. As the spawn occurred under many rocks, there were probably others. Under one rock a small specimen, only 55 mm long, of the Grey Sea Slug, Aeolidia papillosa, had died in the process of laying its eggs, before the spiral had formed on the underside of the rock.

Nudibranch page

Sea Anemones

Sea Anemones were not present in their normal numbers but all the species present in September 1998 were to be found.

Report by Andy Horton
Piddock record
Worthing Pier  19 July 1999

I made a brief visit to Worthing Pier at a low spring of just under 6 metres (at high tide) a few miles to the west of Shoreham-by-Sea during an exceptionally fine day, which had been preceded by a couple of weeks of the hottest and sunniest weather we can expect in southern England, with the shade air temperatures reaching 29° C. During these conditions, the intertidal fauna can be less varied, because the heat dissuades some of the fish and invertebrates that like cooler temperatures from remaining in the shore pools. The water temperature in the rock pools was measured at 22° C early in the morning (about 9.00 am) and the sea itself over the shallow sand at the seaward end of the pierhead measured 20° C, which exceeded the maximum of 19° C I had recorded before over the shallow shrimping grounds off Southwick beach, Sussex and only just below the 21° C recorded in the River Adur estuary at Silver Sands during the hottest sea temperature month of August.

Small Fry in the Small Pools

Small fry were particularly abundant in the shallow pools and it seemed that Blennies were more numerous than previous years.  They were very small, mostly under 20 mm, and some were in their last planktonic larval form with the wing-like pectorals and a length of under 15 mm. The other abundant fish were the gobies and I observed that in the larger pools near low water mark, the larger and proportionately longer of the two sandy gobies found between the tides, the Sand Goby was present in hundreds, whereas in the smaller pools and further up the shore (in the pools north of the pierhead) hundreds of the smaller Common Gobies congregated in similar numbers. Under rocks some tiny, 15 mm long, Rock Gobies darted in between the few pebbles and empty molluscs shells. Small palaemonid prawns and crangoid shrimps also inhabitated the pools and these were just about small enough to be preyed upon by the goby fry (which normally prefer Corophium, caprellids etc.) and certainly would have been swallowed by some very small Bullhead, Taurulus bubalis, fry in the same pools.


The colonial sea-squirt Star Ascidian, Botryllus schlosseri, was recorded yet again as it has for every year since 1994. It had settled on boulders at the end of the pier and on other tunicates attached to rocks. Small Hermit Crabs trundled over the floor of the sandy pools and large specimens of the Hairy Porcelain Crab were evident under rocks.

Sea Anemones were not as common as in most years. Beadlet Anemones were reasonable common with Snakelocks Anemones and Sagartia troglodytes not so prevalent as usual. Plumose Anemones were absent altogether from their normal position drooping down from the pier cross supports and the hot weather was undoubtably the reason. A solitary specimen of Sagartiogeton undatus was discovered on the underside of a boulder and was left there. There may have been more specimens of this anemone.

by Andy Horton

Saturday 31 July 1999
A pod of 12 Bottle-nosed Dolphins, Tursiops truncatus, are seen just 200 metres from the shore. Along the coast at Shoreham-by-Sea, two trawlers are pair-trawling at the same distance form the shore.

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