Year Of Plankton

This year we have launched a Year Of Plankton, an initiative to share interesting plankton facts and photos to help build your plankton knowhow! On this page you will be able to find the latest entry for the week, as well as all entries from previous weeks, in case you missed out.

Week 23 - Sapphirina

Males of the copepod genus Sapphirina shimmer when sunlight bounces off their crystalline exoskeleton, earning them their common name of Sea Sapphire.

 

Their characteristic spiral swimming behaviour accentuates their colours, with flashes of blue, violet, red and yellow at every twist and turn. In contrast, females are almost transparent in colour, have large eyes and parasitise large gelatinous creatures called salps; individuals enter the salp using hooks on their antennae and feed on the internal body tissue.

Males however are too large to fit inside salps, and as they have a reduced gut, scientists believe some do not feed at all during their adult stage.

Week 22 - Coscinodiscus

Algae, like these Coscinodiscus, are some of nature’s most effective solar powered organisms. Their glass-like cell walls are made from silica, and are covered in pores arranged in complex symmetrical patterns, allowing light to flow into the organism without letting any escape.

In European waters, the non-native diatom, Coscinodiscus wailesii, can occur in huge numbers, often forming up to 90% of the total algal biomass. However, due to its large size, it is inedible to most zooplankton. This bloom-forming species was first recorded in the CPR Survey in 1977, thought to have been introduced by either ballast water or through oyster imports. It is important to monitor this species as in large numbers, it produces copious amounts of mucilage (slime) which can blanket the seabed, threatening benthic species.

Photo credit: thanks to Robert Lavigne from www.microscopyview.com for permission to share both images

Week 21 - Zoothamnium

This mass of cells is actually a colony of Zoothamnium, a genus of marine ciliate.

Each cell is connected to a central stalk containing a contracting band, which allows the whole colony to contract and move in unison.

 

These colonies often attach themselves to planktonic crustaceans and can sometimes be so dense, they affect the swimming and feeding ability of the host.

When the host dies, the individual cells can dissolve from the colony and float freely, for up to 12 hours, allowing them to drift to a more favourable location or a new host.

Week 20 - Lucicutia

Lucicutia, the shining stars of deep-sea plankton appear to glow in the water.

These copepods, first identified by taxonomists Giesbrecht and Schmeil in 1898, were named Lucicutia, which comes from the Latin LUX (meaning light) and CUTIS (meaning skin).

Today we know that it is not the skin of these animals that glows, but that glands on their bodies secrete bioluminescent material into the surrounding waters.

Although the majority of Lucicutia species spend most of their time in deep water (200m),  we often spot 1 or 2 species on our CPR silks from samples collected at night.

Week 19 - Caligus

The copepod genus Caligus, commonly known as fish lice, parasitise a wide range of farmed and wild fish species. 

Their vampiric and flesh eating feeding behaviour can have a serious effect on the host, compromising immunity, with severe infestations often proving fatal. 

So called ‘epidemics’ of fish lice have been seen to drive up the price of farmed salmon and there is growing concern that global warming may further fuel plagues of these parasites, as warmer waters allow them to breed in larger numbers.

Week 18 - Phronima

Phronima are small amphipods (crustaceans) found in the deep sea, though they come to the surface to feed at night.

They bear a startling resemblance to the Alien queen from the movies, and this terrifying appearance (albeit on a miniature scale!) doesn’t stop just at the looks.

 

Phronima like nothing better than feeding on the insides of barrel-like salps (animals similar to jellyfish), and then using the gelatinous body of the host as a mini-submarine, as transport and a nursery for their developing eggs!

Week 17 - Echinoderm larvae

Starfish, sea urchins and sea cucumbers all belong to the taxonomic group (phylum) Echinodermata, and are exclusively marine.

During spring and summer months, adults release eggs and sperm straight into the water.

 

Fertilised eggs then develop into the first of many larval stages, which depending on the species, last between a few days to several weeks, before they develop into an adult form.

As in many marine animals, the planktonic larval form bears little resemblance to the adults’ form, with some looking more like human ears or spaceships than starfish!

 

Week 16 - Asterionellopsis glacialis

The phytoplankton (algae) Asterionellopsis glacialis, thrives in turbulent waters and is often referred to as a ‘surf diatom’.

 

Despite being cosmopolitan in distribution, this species often accumulates in high numbers in the surf zone (where waves break), appearing to favour this extreme environment.

Due to proximity to coastal areas, surf diatoms are particularly sensitive to changes in surf zone dynamics, for example, sediment deposition caused by dredging or increased rainfall.

Week 15 - Penilia avirostris

Penilia avirostris is one of the few truly marine species of the order Cladocera, commonly known as water-fleas.

This species is not native to UK waters, with theories of its introduction including both warming sea surface temperatures and an increase in anthropogenic activities (through ballast water transport).

 

Over the last two decades, this species has expanded its range further north and is now an important component of the summer plankton community in the North Sea.

Week 14 - Dinophysis norvegica

They may be microscopic but these phytoplankton have the potential to make you ill.

Dinophysis norvegica is a bloom-forming toxic species associated with Diarrhetic Shellfish Poisoning (DSP) events around the world.

 These organisms can bioaccumulate (build-up) in shellfish, which when eaten by humans, can cause sickness. These DSP events can cause shellfish farms to close temporarily, causing a significant loss in revenue – by monitoring the distribution and abundance of species like these, suitable management action can be taken to prevent this happening.

Week 13 - Fish larvae

Did you know fish begin life as eggs and larvae in the plankton, drifting with the ocean’s currents?

When larval fish first hatch, their mouths and gills are not fully developed; young must rely on an internal yolk sac for food and absorb oxygen through their developing fins for the first few days of their life.

Once they are able to feed, species like these cod initially feed on copepod nauplii (juveniles) before actively seeking larger copepods, like Calanus finmarchicus (pictured here).

Week 12 - Oncaea

These brightly coloured copepods have a surprisingly dark feeding habit.

Using sensory organs (as they lack an image forming eye) members of the genus Oncaea locate large zooplankton, like arrow worms, in the water around them, and latch on using their antennae and maxillipeds (specialised feeding limbs).

They begin by grazing on food particles stuck to the outside of the host’s body, before piercing the host’s body wall and feeding on the body fluids inside!

Week 11 - Spring bloom

Did you know the oceans experience spring too?

During winter, rough seas increase mixing of the water column, re-suspending nutrients and phytoplankton cysts (resting stages of phytoplankton).

As spring arrives, with longer days and increasing light and temperature levels, diatoms like these are able to reproduce rapidly, leading to an event known as the spring bloom.

 

Although these organisms are microscopic, spring blooms can often be seen from space!

Week 10 - Tripos arcticus

Tripos arcticus is a cold water phytoplankton species from the Genus Tripos.

This species can bloom in very high numbers during winter months as they not only photosynthesise, like a plant, but also ingest smaller organisms too, like an animal.

During these blooms, T. arcticus can reproduce so rapidly the colour of the water can change to a reddish/brown colour, and in extreme cases, oxygen levels can become depleted, an event known as a Harmful Algal Bloom.

Week 9 - Calanus hyperboreus

Meet the deep water copepod, Calanus hyperboreus, an animal which dominates the Arctic Ocean in number.

 

It grazes on algae growing on the underside of the sea ice and on free-floating phytoplankton, and is sometimes referred to as the “little cow of the ocean”.

These food sources are important to help it maintain a high fat content, to help sustain it through the long dark winters.

In the Arctic, fats are the currency of life, and these copepods form the primary food source for many larger marine species, including Arctic cod.

Week 8 - Branchiostoma lanceolatum

These fish-like animals are called Lancelets and the closest living relatives of all vertebrates

Their body is supported by a primitive back-bone called a notochord, which prevents their bodies collapsing as they swim.

Scientists have been studying these animals as it’s believed they hold many clues to the evolution and development of all living vertebrates!

The most well-known representative from this group is the Branchiostoma lanceolatum, as seen in these pictures.

Week 7 - Pterosperma

Pterosperma are recorded in the CPR Survey in their non-mobile cyst, or phycoma, stage, and look very similar to little flying saucers when viewed from above. They can be identified by their dense, inner structure, which can have single or multiple 'wings' or ala, often in circumference around the body.

Despite the species being poorly studied, it has been routinely recorded in the CPR Survey over the last few years and has an oceanic distribution in the North Atlantic, recorded throughout the year often during periods of high phytoplankton biomass (blooms).

Week 6 - Neodenticula seminae

The distinctive domino-like, chain-forming diatom Neodenticula seminae is considered the first plankton species to have made the crossing from the Pacific to the Atlantic Ocean via the increasingly ice-free Arctic. This species was last found in sediment records in the Atlantic from approx. 800,000 years ago. 

However, with the ice barrier reduced, a large volume of Pacific water first entered the Northwest Atlantic in summer 1998, carrying with it this diatom (there had been no shipping via this route, so ballast water transport has been dismissed). Since then the species has re-established itself across the northern North Atlantic.

Week 5 - Decapod megalopa

The crab equivalent of human teenage years is know as decapod megalopa! This name comes from the Latin meaning '10-footed' (Dec=10, pod=foot) referring to the 10 limbs all crabs have, and its stage 'megalopa' mega=big and lop=eyes, referring to the physical changes the crab goes through as it develops.

 

This megalopa stage is the final stage that occurs in the plankton, before the animal settles on to the sea floor and transforms into what we recognise as a crab.


 

Week 4 - Decapod zoea

Once thought to be separate species, we now know that zoea are juvenile stages of crabs, lobsters, crayfish, prawns + shrimp.

       

 Antonie van Leeuwenhoek, “The Father of Microbiology” was, in 1699, the first person to describe the differences between the larval stages of crustaceans and their adult forms. Despite this, controversy remained about whether or not metamorphosis occurred in crustaceans due to observations based on different species, some of which do not metamorphosise. This controversy persisted until the 1840s and it was not until the 1870s that the first complete series of descriptions of crustacean larval forms were published.


Week 3 - Miracia spp.

Juveniles of the brilliant blue copepod Miracia spp. have to cling for life on ‘rafts’ of blue green algae, namely the filamentous cyanobacteria Trichodesmium. In the open ocean suitable substrates for the development of Miracia spp. are scarce, and Trichodesmium provides both a source of food as well as being a floatation aid to kickstart their development.

  


 Week 2 - Noctiluca scintillans

When disturbed, these marine dinoflagellates (Noctiluca scintillans) glow, or bioluminesce – it’s easy to see why their common name is Sea Sparkle!

Unlike most dinoflagellates, N. scintillans do not feed via photosynthesis, instead they use their feeding tentacle to capture passing food such as diatoms and copepods! Check out their tentacles searching for food in this video clip! 

           


Week 1 - Cirripede

Did you know that before gluing themselves to rocks, juvenile barnacles begin life drifting in the plankton?

The early stage's of a barnacle's life include 2 free swimming stages, a nauplius and cypris stage, before they develop into adults and attach themselves to rocks.

Cirripede cypris  Cirripede nauplii      

Adult barnacles feed by pushing their feet through their 'trapdoor' roofs and waving them around to catch passing food! The last photo is of a barnacle exuvium - a complete exoskeleton an adult barnacle has shed in a moult - can you see the basket-like feeding limbs?

 Barnacle exuvium

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