Alex Hyde / Wolf Spider (Xerolycosa nemoralis) female carrying egg sac, photographd on a white background. Aosta Valley, Monte Rosa Massif, Pennine Alps, Italy. July.

Wild Wonders of Europe / Benvie / Female Raft spider (Dolomedes fimbriatus) carrying egg sac, Fliess, Naturpark Kaunergrat, Tirol, Austria, July 2008

Wild Wonders of Europe / Benvie / Female Raft spider (Dolomedes fimbriatus) with egg sac, Fliess, Naturpark Kaunergrat, Tirol, Austria, July 2008

Piotr Naskrecki / Eggs of an unidentified insect, Guinea, West Africa

Gerry Ellis / Wandering Spider (Cupiennius coccineus) with egg sac under abdomen, not visible in photo, Mesoamerica

Jeff Rotman / Newly hatched Spined pygmy shark still attached to egg sac (Squalilus laticaudatus) Mediterranean

John Cancalosi / Nursery web spider (Pisauridae) carrying egg sac, tropical rainforest, Costa Rica

John Cancalosi / Nursery web spider (Pisauridae) carrying egg sac, tropical rainforest, Costa Rica

Alex Hyde / Wolf Spider (Xerolycosa nemoralis) female carrying egg sac, photographd on a white background. Aosta Valley, Monte Rosa Massif, Pennine Alps, Italy. July.

Alex Hyde / Silk egg sac of Cucumber Spider (Araniella cucurbitina) Aosta Valley, Monte Rosa Massif, Pennine Alps, Italy. July.

Alex Hyde / Wolf Spider female (Pardosa lugubris) carrying egg sac. Peak District National Park, Derbyshire, UK. June.

Alex Hyde / Female jumping spider (Euophrys frontalis) guarding egg sac underneath a stone in disused limestone quarry, Peak District National Park, Derbyshire, UK. June.

Alex Hyde / Female Jumping spider (Euophrys frontalis) guarding egg sac underneath a stone in disused limestone quarry, Peak District National Park, Derbyshire, UK. June.

Alex Hyde / Common Crawler spider (Zelotes latreillei) female guarding her egg sac beneath a stone, Peak District National Park, Derbyshire, UK. June.

Stephen Dalton / Cave Spider (Meta menardi) female with egg-sac, male above. UK, August.

Stephen Dalton / Cave Spider (Meta menardi) female with egg-sac. UK, August.

Stephen Dalton / Cave Spider (Meta menardi) female with egg-sac. UK, August.

Stephen Dalton / Cave Spider (Meta menardi) female with egg-sac. UK, August.

Nick Upton / Female Comb footed spider (Enoplognatha ovata or latimana) guarding egg sac in silk shelter on grass seedhead, chalk grassland meadow, Wiltshire, UK, August.

MYN / Clay Bolt / Green lynx spider (Peucetia viridans) female with egg-sac, Dacusville, North Carolina, USA, October, meetyourneighbours.net project

James Christensen / Wandering Spider (Cupiennius bimaculatus) female with egg sac at the entrance to her lair within a bromeliad, Mindo, western slope of Andes, Ecuador

Bernard Castelein / Nursery web spider (Pisaura mirabilis) female with egg sac on bracken, Brasschaat, Belgium, June

Ross Hoddinott / 2020VISION / Spider with egg sac, on sphagnum moss and Common / Round leaved sundew {Drosera rotundifolia}, Westhay Nature Reserve (Somerset Wildlife Trust), Somerset Levels, Somerset, UK. June

Nick Upton / Female Nursery Web Spider (Pisaura mirabilis) holding her egg sac in sunshine to speed egg development. Wiltshire garden, UK, May.

Florian Möllers / European sac spider (Cheiracanthium punctorium) female at egg sac, Gosener Wiesen reserve, Berlin, Germany. July

Fabio Liverani / Freshwater Crab (Potamon fluviatile) female with ventral egg sac exposed by researcher. Foreste Casentinesi National Park, Italy, July.

Fabio Liverani / Freshwater Crab (Potamon fluviatile) female with ventral egg sac exposed by researcher. Foreste Casentinesi National Park, Italy, July.

Chien Lee / Giant Crab Spider (Sparassidae) female with her egg sac, Kubah National Park, Sarawak, Borneo, Malaysia

Chien Lee / Giant Crab Spider (Sparassidae) female carrying her egg sac, Gunung Mulu National Park, Malaysia

Russell Cooper / Female Spotted wolf spider (Pardosa amentata) carrying egg sac, South London, UK, July

Gerry Ellis / Huntsman Spider (Cupiennius coccineus) with egg sac, North America

Georgette Douwma / Brownbanded bamboo shark (Chiloscyllium punctatum), juvenile with egg sac still attached. Komodo National Park, Indonesia.

Rolf Nussbaumer / Close up of Black Horse fly (Tabanus atratus)female laying egg sac, Fennessey Ranch, Refugio, Corpus Christi, Coastal Bend, Texas Coast, USA

Murray Cooper / Huntsman Spider (Micrommata sp) mother with egg-sac, Ecuador

Chien Lee / Giant Crab Spider (Sparassidae) female carrying her egg sac, Borneo, Malaysia

Stephen Dalton / Daddy long legs spider {Pholcus phalangioides} with egg-sac, walking upside-down on ceiling, UK, Pholcidae

Stephen Dalton / Pirate pond spider (Pirata piraticus) on pond with egg-sac, UK, Lycosidae

Stephen Dalton / Daddy long legs spider (Pholcus phalangioides) on web with egg sac, UK, Pholcidae

Stephen Dalton / Egg sac of Ray spider (Theridiosoma gemmosum) hanging from leaf, UK

Stephen Dalton / Egg sac of Ray spider (Theridiosoma gemmosum) hanging from plant stem, UK, Theridiosomatidae

Stephen Dalton / American house spider (Achaearenia tepidariorum) with egg sac, USA, Theridiidae

Stephen Dalton / Egg sac of Scaffold spider (Theridion pallens) UK. Therididae

Stephen Dalton / American house spider {Parasteatoda tepidariorum} embryo spiderlings in egg sac, USA

Stephen Dalton / Pond pirate spider (Pirata sp) with egg sac on pond, UK, Lycosidae

Stephen Dalton / Egg sac of Scaffold web spider (Theridion pallens) attached to underside of leaf, UK

Stephen Dalton / Female Cave spider (Meta menardi) with egg-sac, UK

Stephen Dalton / Cave spider (Meta menardi) pair with egg-sac, UK

Stephen Dalton / Ghost spider (Zora sp) guarding egg sac, UK

Stephen Dalton / Orb weaver spider (Agalenatea redii) guards its egg sac on plant stem, UK

Stephen Dalton / Nursery web spider (Pisaura sp) carrying egg sac, Cyprus

Stephen Dalton / Female Cave spider (Meta menardi) with egg-sac, UK

Stephen Dalton / Grasshead prowler spider (Cheiracanthium erraticum) egg sac on grass, UK

Stephen Dalton / Female Cave spider (Meta menardi) with egg-sac, UK

Stephen Dalton / Nursery web spider (Pisaura mirabilis) with egg-sac, UK, Pisauridae

Stephen Dalton / Wasp spider (Argiope bruennichi) with egg sac, UK, Araneidae

Stephen Dalton / Wolf spider (Pardosa sp) with egg-sac, on bark, UK, Lycosidae

Stephen Dalton / Daddy long legs spider {Pholcus phalangioides} with egg-sac, UK, Pholcidae

Stephen Dalton / Two Daddy long legs spiders {Pholcus phalangioides} one on left with egg-sac, UK, Pholcidae

Ingo Arndt / Amu-Darya Trout (Salmo trutta trutta) egg with alevin already visible through egg-shell, Europe

Fabio Liverani / Wolf spider (Pardosa wagleri) carrying egg sac through shallow water, Lake Cernika, Slovenia

Fabio Liverani / Wolf spider (Pardosa wagleri) carrying egg sac through shallow water, Lake Cernika, Slovenia

John Cancalosi / Raft spider (Dolomedes spp) with egg sac, New York, USA

Ingo Arndt / Brown Trout (Salmo trutta) alevin hatching from egg with full yolk sac, Europe

Andy Sands / Daddy longlegs spider (Pholcus phalangioides) carrying egg sac, inside garden shed, Hertfordshire, England, UK

Andy Sands / False widow / Cellar spider (Steatoda grossa), protecting egg-sac in corner of room in domestic house, Hertfordshire, England, UK.

Andy Sands / False widow / Cellar spider (Steatoda grossa), protecting egg-sac in corner of room in domestic house, Hertfordshire, England, UK.

Alex Hyde / Female Nursery web spider {Pisaura mirabilis} carrying egg sac, Peak District National Park, Derbyshire, UK

Russell Cooper / Raft spider {Dolomedes fimbriatus} female protecting her egg sac, UK

Michael Quinton / Wolf Spider (Lycosidae) female with egg sac, Alaska

Jose B. Ruiz / Nursery web spider {Pisaura mirabilis} with egg sac, Potes, Picos de Europa, Asturias, Spain

Jose B. Ruiz / Nursery web spider {Pisaura mirabilis} with egg sac, Potes, Picos de Europa, Asturias, Spain

Albert Lleal / Brine Shrimp (Artemia salina) egg sac close up, Spain

Albert Lleal / Brine Shrimp (Artemia salina) ventral view, female showing an egg sac, Spain

SINCLAIR STAMMERS / Raft spider (Dolomedes fimbriatus) warming egg sac amongst wetland plants. Chobham common, Surrey, England

SINCLAIR STAMMERS / Raft spider (Dolomedes fimbriatus) warming an egg sac in the sun, amongst wetland plants. Chobham common, Surrey, England

Andy Sands / Nursery Web Spider (Pisaura mirabilis) Female carrying egg sac, Hertfordshire, UK

PREMAPHOTOS / Female spider {Aphantochilus sp} mimicking an Ant {Cephalotes sp.} guarding her egg-sac, Peru

PREMAPHOTOS / Female Common crawler spider {Zelotes latreillei} guarding her egg-sac beneath a stone, UK

PREMAPHOTOS / Female Crab spider {Xysticus cristatus} guarding egg-sac, UK

Mark Moffett / Wolf Spider (Lycosidae) close up portrait with egg sac, Tiputini, Ecuador

Piotr Naskrecki / Red-eyed Tree Frog (Agalychnis callidryas) embryos in egg sacs, a few days old, Costa Rica

Andrew Cooper / Cave spider with egg sac (Meta menardii) Devon UK England

Kim Taylor / Meadow Spider {Pardosa saltans} female carrying egg sac, Surrey, England.

Kim Taylor / Meadow / Wolf Spider {Pardosa amentata} female carrying egg sac, Surrey, England.

Klaus Echle / Raft spider {Dolomedes fimbriatus} protecting egg coccoon, Germany

Jeff Rotman / Premature Great blue shark {Prionace glauca} with egg sac, New England, USA.

Todd Pusser / Tiger salamander {Ambystoma tigrinum} egg sac, North Carolina, USA. Goose Pond Bay

Rod Williams / Black widow spider {Latrodectus mactans} female with egg sac, South America.

Rod Williams / Black widow spider {Latrodectus mactans} female with egg sac, South America.

Kim Taylor / Nursery web wolf spider {Pisaura mirabilis} carrying egg sac, UK.

Kim Taylor / Spider {Enoplognatha ovata} female with egg sac on nettle leaf. UK.

Kim Taylor / Tawny cockroach {Ectobius pallidus} female with egg sac on grass stem, Europe

Duncan Usher / Raft Spider (Dolomedes fimbriatus) female carrying egg sac, Europe

Dietmar Nill / Wolf spider with egg sac {Lycosidae} Bulgaria

Andrew Cooper / Cave spider with egg sac (Meta menardii) Devon UK England

Duncan Mcewan / Spider with egg sac {Enoplognatha ovata} Scotland, UK